### User Instance Example

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

An example of creating a User instance.

```swift
let shayne = User(primaryKey: 2, name: "Shayne")
```

--------------------------------

### User Model Example

Source: https://github.com/instagram/iglistkit/blob/main/docs/getting-started.html

An example of a User model before conforming to ListDiffable.

```swift
class User {
  let primaryKey: Int
  let name: String
  // implementation, etc
}

```

--------------------------------

### User Model Example

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

An example of a User model that will be used to demonstrate diffing.

```swift
class User {
  let primaryKey: Int
  let name: String
  // implementation, etc
}
```

--------------------------------

### UICollectionView and IGListAdapter Setup

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

Setting up a UICollectionView and IGListAdapter.

```swift
let layout = UICollectionViewFlowLayout()
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)

let updater = ListAdapterUpdater()
let adapter = ListAdapter(updater: updater, viewController: self)
adapter.collectionView = collectionView
```

--------------------------------

### User Model Conforming to ListDiffable

Source: https://github.com/instagram/iglistkit/blob/main/docs/getting-started.html

Example of conforming a User model to the ListDiffable protocol.

```swift
extension User: ListDiffable {
  func diffIdentifier() -> NSObjectProtocol {
    return primaryKey
  }

  func isEqual(toDiffableObject object: Any?) -> Bool {
    if let object = object as? User {
      return name == object.name
    }
    return false
  }
}

```

--------------------------------

### Initializing ListAdapter with Working Range

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

Example of initializing ListAdapter with a working range size.

```swift
let adapter = ListAdapter(updater: ListAdapterUpdater(),
                   viewController: self,
                 workingRangeSize: 1) // 1 before/after visible objects
```

--------------------------------

### Updated User Instance Example

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

An example of an updated User instance with the same primary key but a different name.

```swift
let ann = User(primaryKey: 2, name: "Ann")
```

--------------------------------

### Using ListDiff Outside of IGListAdapter

Source: https://github.com/instagram/iglistkit/blob/main/docs/getting-started.html

Demonstrates using the ListDiff algorithm directly.

```swift
let result = ListDiff(oldArray: oldUsers, newArray: newUsers, .equality)

```

--------------------------------

### Install with Carthage

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Installation.md

Add this to your Cartfile if using Carthage.

```ogdl
github "Instagram/IGListKit" ~> 4.0
```

--------------------------------

### IGListAdapter Data Source Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

Implementing the data source methods for IGListAdapter.

```swift
func objects(for listAdapter: ListAdapter) -> [ListDiffable] {
  // this can be anything!
  return [ "Foo", "Bar", 42, "Biz" ]
}

func listAdapter(_ listAdapter: ListAdapter, sectionControllerFor object: Any) -> ListSectionController {
  if object is String {
    return LabelSectionController()
  } else {
    return NumberSectionController()
  }
}

func emptyView(for listAdapter: ListAdapter) -> UIView? {
  return nil
}
```

--------------------------------

### LabelSectionController Example

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

An example of a section controller that handles a String and configures a single cell with a UILabel.

```swift
class LabelSectionController: ListSectionController {
  override func sizeForItem(at index: Int) -> CGSize {
    return CGSize(width: collectionContext!.containerSize.width, height: 55)
  }

  override func cellForItem(at index: Int) -> UICollectionViewCell {
    return collectionContext!.dequeueReusableCell(of: MyCell.self, for: self, at: index)
  }
}
```

--------------------------------

### Using ListDiff Outside of IGListAdapter

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

Demonstrates how to use the diffing algorithm independently of IGListAdapter.

```swift
let result = ListDiff(oldArray: oldUsers, newArray: newUsers, .equality)
```

--------------------------------

### Import IGListKit

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Installation.md

Import statement for both full library and diffing components.

```swift
import IGListKit
```

--------------------------------

### CocoaPods Installation

Source: https://github.com/instagram/iglistkit/blob/main/README.md

The preferred installation method is with CocoaPods. Add the following to your Podfile:

```ruby
pod 'IGListKit', '~> 5.2.0'
```

--------------------------------

### Carthage Installation

Source: https://github.com/instagram/iglistkit/blob/main/README.md

For Carthage, add the following to your Cartfile:

```ogdl
github "Instagram/IGListKit" ~> 5.2.0
```

--------------------------------

### Install from Main Branch with CocoaPods

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Installation.md

Use the latest version from the main branch, which is stable and reliable.

```ruby
pod 'IGListKit', :git => 'https://github.com/Instagram/IGListKit.git', :branch => 'main'
```

--------------------------------

### Install Diffing Subspec with CocoaPods

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Installation.md

Use this if you only need the diffing components of IGListKit.

```ruby
pod 'IGListKit/Diffing', '~> 4.0'
```

--------------------------------

### Wrapper Model Example

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Best Practices and FAQ.md

An example of creating a wrapper model for use in section controllers.

```swift
class WeatherSectionModel {
  let location: Location
  let forecast: Forecast
  let conditions: Conditions
}
```

--------------------------------

### Install Latest Release with CocoaPods

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Installation.md

Add this to your Podfile to use the latest release of IGListKit.

```ruby
pod 'IGListKit', '~> 4.0'
```

--------------------------------

### Connecting Data Source to Adapter

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

Connecting the data source to the IGListAdapter by setting its dataSource property.

```swift
adapter.dataSource = self
```

--------------------------------

### IGListDiffable Conformance

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Getting Started.md

Implementing the ListDiffable protocol for the User model to enable custom diffing.

```swift
extension User: ListDiffable {
  func diffIdentifier() -> NSObjectProtocol {
    return primaryKey
  }

  func isEqual(toDiffableObject object: Any?) -> Bool {
    if let object = object as? User {
      return name == object.name
    }
    return false
  }
}
```

--------------------------------

### Wrapper Model Example

Source: https://github.com/instagram/iglistkit/blob/main/docs/best-practices-and-faq.html

Example of creating a wrapper model for use in section controllers and making it diffable.

```swift
class WeatherSectionModel {
  let location: Location
  let forecast: Forecast
  let conditions: Conditions
}

extension WeatherSectionModel: ListDiffable {
  func diffIdentifier() -> NSObjectProtocol {
    return location.identifier
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    guard self !== object else { return true }
    guard let object = object as? WeatherSectionModel else { return false }
    return location == object.location && forecast == object.forecast && conditions == object.conditions
  }
}
```

--------------------------------

### Diffable Object Example

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Example of implementing diffable object protocol for a post.

```swift
func diffIdentifier() -> NSObjectProtocol {
      return (username + timestamp) as NSObjectProtocol
    }
    
    // 2
    func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
      return true
    }
```

--------------------------------

### User NSManagedObject

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Working with Core Data.md

Example of a User NSManagedObject with properties.

```swift
extension User {
    @NSManaged var firstName: String
    @NSManaged var lastName: String
    @NSManaged var address: String
    @NSManaged var someVariableNotNeededInUI: String
}
```

--------------------------------

### Swift Batch Update Example

Source: https://github.com/instagram/iglistkit/blob/main/docs/migration.html

Demonstrates how to perform item mutations within a batch update block in Swift.

```swift
// OLD
expanded = true
collectionContext?.insert(in: self, at: [0])

// NEW
collectionContext?.performBatch(animated: true, updates: { (batchContext) in
  self.expanded = true
  batchContext.insert(in: self, at: [0])
})

```

--------------------------------

### Dynamic Array Example

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Best Practices and FAQ.md

An example of a model that owns an array to power numberOfItems, demonstrating how to check for array changes for diffing.

```swift
class Forecast: ListDiffable {
  let day: Date
  let hourly: [HourlyForecast]

  func diffIdentifier() -> NSObjectProtocol {
    return day
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    guard self !== object else { return true }
    guard let object = object as? Forecast else { return false }
    return hourly == object.hourly // compare elements in the arrays
  }
}
```

--------------------------------

### PostSectionController.swift

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Initial setup for PostSectionController, subclassing ListBindingSectionController and setting the data source.

```swift
final class PostSectionController: ListBindingSectionController<Post>,
ListBindingSectionControllerDataSource {

  override init() {
    super.init()
    dataSource = self
  }

}
```

--------------------------------

### Objective-C Batch Update Example

Source: https://github.com/instagram/iglistkit/blob/main/docs/migration.html

Demonstrates how to perform item mutations within a batch update block in Objective-C.

```objective-c
// OLD
self.expanded = YES;
[self.collectionContext insertInSectionController:self atIndexes:[NSIndexSet indexSetWithIndex:]];

// NEW
[self.collectionContext performBatchAnimated:YES updates:^(id<IGListBatchContext> batchContext) {
  self.expanded = YES;
  [batchContext insertInSectionController:self atIndexes:[NSIndexSet indexSetWithIndex:1]];
} completion:nil];

```

--------------------------------

### ListBindable Implementations

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Example Swift code demonstrating ListBindable implementations for ActionCell, UserCell, and CommentCell.

```swift
final class ActionCell: UICollectionViewCell, ListBindable {
  @IBOutlet weak var likesLabel: UILabel!
  @IBOutlet weak var likeButton: UIButton!

  // MARK: ListBindable
  func bindViewModel(_ viewModel: Any) {
    guard let viewModel = viewModel as? ActionViewModel else {
      return
    }
    likesLabel.text = "\(viewModel.likes)"
  }
}

final class UserCell: UICollectionViewCell, ListBindable {
  @IBOutlet weak var usernameLabel: UILabel!
  @IBOutlet weak var dateLabel: UILabel!

  // MARK: ListBindable
  func bindViewModel(_ viewModel: Any) {
    guard let viewModel = viewModel as? UserViewModel else {
      return
    }
    usernameLabel.text = viewModel.username
    dateLabel.text = viewModel.timestamp
  }
}

final class CommentCell: UICollectionViewCell, ListBindable {
  @IBOutlet weak var usernameLabel: UILabel!
  @IBOutlet weak var commentLabel: UILabel!

  // MARK: ListBindable
  func bindViewModel(_ viewModel: Any) {
    guard let viewModel = viewModel as? Comment else {
      return
    }
    usernameLabel.text = viewModel.username
    commentLabel.text = viewModel.text
  }
}
```

--------------------------------

### IGListDiffable bare minimum

Source: https://github.com/instagram/iglistkit/blob/main/Guides/IGListDiffable and Equality.md

The quickest way to get started with diffable models is use the object itself as the identifier, and use the superclass's -[NSObject isEqual:] implementation for equality.

```objc
- (id<NSObject>)diffIdentifier {
  return self;
}

- (BOOL)isEqualToDiffableObject:(id<IGListDiffable>)object {
  return [self isEqual:object];
}
```

--------------------------------

### PersonModel.value example

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Generating your models using remodel.md

Example of a .value file defining a PersonModel that includes IGListDiffable.

```remodel
# PersonModel.value
PersonModel includes(IGListDiffable) {
  NSString *firstName
  NSString *lastName
  %diffIdentifier
  NSString *uniqueId
}
```

--------------------------------

### UserCell Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Example of a UserCell conforming to ListBindable to bind a UserViewModel.

```swift
final class UserCell: UICollectionViewCell, ListBindable {

  @IBOutlet weak var usernameLabel: UILabel!
  @IBOutlet weak var dateLabel: UILabel!

  // MARK: ListBindable

  func bindViewModel(_ viewModel: Any) {
    guard let viewModel = viewModel as? UserViewModel else { return }
    usernameLabel.text = viewModel.username
    dateLabel.text = viewModel.timestamp
  }

}
```

--------------------------------

### Post Model Implementation

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Example of a Post model conforming to ListDiffable, holding data for a list item.

```swift
import IGListKit

final class Post: ListDiffable {

  // 1
  let username: String
  let timestamp: String
  let imageURL: URL
  let likes: Int
  let comments: [Comment]

  // 2
  init(username: String, timestamp: String, imageURL: URL, likes: Int, comments: [Comment]) {
    self.username = username
    self.timestamp = timestamp
    self.imageURL = imageURL
    self.likes = likes
    self.comments = comments
  }

}


// MARK: ListDiffable

func diffIdentifier() -> NSObjectProtocol {
  // 1
```

--------------------------------

### Updating listAdapter delegate method

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Example of updating the listAdapter delegate method to return PostSectionController.

```swift
func listAdapter(
  _ listAdapter: ListAdapter,
  sectionControllerFor object: Any
  ) -> ListSectionController {
  return PostSectionController()
}
```

--------------------------------

### User model equality methods

Source: https://github.com/instagram/iglistkit/blob/main/Guides/IGListDiffable and Equality.md

Example implementation of equality methods for a User model with identifier, name, and posts properties.

```objc
@implementation User

- (NSUInteger)hash {
  return self.identifier;
}

- (BOOL)isEqual:(id)object {
  if (self == object) {
      return YES;
  }
  
  if (![object isKindOfClass:[User class]]) {
      return NO;
  }

  User *right = object;
  return self.identifier == right.identifier 
      && (self.name == right.name || [self.name isEqual:right.name])
      && (self.posts == right.posts || [self.posts isEqualToArray:right.posts]);
}

@end
```

--------------------------------

### IGListDiffable bare minimum

Source: https://github.com/instagram/iglistkit/blob/main/docs/iglistdiffable-and-equality.html

The quickest way to get started with diffable models is to use the object itself as the identifier, and use the superclass’s -[NSObject isEqual:] implementation for equality.

```objective-c
- (id<NSObject>)diffIdentifier {
  return self;
}

- (BOOL)isEqualToDiffableObject:(id<IGListDiffable>)object {
  return [self isEqual:object];
}

```

--------------------------------

### ActionCell Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Example of an ActionCell conforming to ListBindable to bind an ActionViewModel.

```swift
final class ActionCell: UICollectionViewCell, ListBindable {

  @IBOutlet weak var likesLabel: UILabel!
  @IBOutlet weak var likeButton: UIButton!

  // MARK: ListBindable

  func bindViewModel(_ viewModel: Any) {
    guard let viewModel = viewModel as? ActionViewModel else { return }
    likesLabel.text = "\(viewModel.likes)"
  }

}
```

--------------------------------

### IGListDiffable Conformance (Swift)

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Migration.md

Example of conforming to IGListDiffable in Swift to maintain previous behavior.

```swift
import IGListKit

extension MyModel: ListDiffable {
  func diffIdentifier() -> NSObjectProtocol {
    return self
  }
  
  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    return isEqual(object)
  }
}
```

--------------------------------

### Displaying in the View Controller

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Example Swift code to add a Post object to the data array in a ViewController.

```swift
data.append(Post(
  username: "@janedoe",
  timestamp: "15min",
  imageURL: URL(string: "https://placekitten.com/g/375/250")!,
  likes: 384,
  comments: [
    Comment(username: "@ryan", text: "this is beautiful!"),
    Comment(username: "@jsq", text: "😱"),
    Comment(username: "@caitlin", text: "#blessed"),
  ]
))

```

--------------------------------

### Swift Item Mutations

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Migration.md

Example of how to perform item mutations within a batch block in Swift.

```swift
// OLD
expanded = true
collectionContext?.insert(in: self, at: [0])

// NEW
collectionContext?.performBatch(animated: true, updates: { (batchContext) in
  self.expanded = true
  batchContext.insert(in: self, at: [0])
})
```

--------------------------------

### CommentCell Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Example of a CommentCell conforming to ListBindable to bind a Comment object.

```swift
final class CommentCell: UICollectionViewCell, ListBindable {

  @IBOutlet weak var usernameLabel: UILabel!
  @IBOutlet weak var commentLabel: UILabel!

  // MARK: ListBindable

  func bindViewModel(_ viewModel: Any) {
    guard let viewModel = viewModel as? Comment else { return }
    usernameLabel.text = viewModel.username
    commentLabel.text = viewModel.text
  }

}
```

--------------------------------

### ImageCell Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Example of an ImageCell conforming to ListBindable to bind an ImageViewModel.

```swift
import UIKit
import SDWebImage
import IGListKit

final class ImageCell: UICollectionViewCell, ListBindable {

  @IBOutlet weak var imageView: UIImageView!

  // MARK: ListBindable

  func bindViewModel(_ viewModel: Any) {
    guard let viewModel = viewModel as? ImageViewModel else { return }
    imageView.sd_setImage(with: viewModel.url)
  }

}
```

--------------------------------

### Adding Data to ViewController

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Example of adding a Post object to the data array in ViewController.swift.

```swift
data.append(Post(
  username: "@janedoe",
  timestamp: "15min",
  imageURL: URL(string: "https://placekitten.com/g/375/250")!,
  likes: 384,
  comments: [
    Comment(username: "@ryan", text: "this is beautiful!"),
    Comment(username: "@jsq", text: "😱"),
    Comment(username: "@caitlin", text: "#blessed"),
  ]
))
```

--------------------------------

### Registering the iglistdiffable plugin

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Generating your models using remodel.md

Example of how to register the 'iglistdiffable' plugin in the remodel configuration file.

```typescript
// value-object-default-config.ts
basePlugins: List.of(
    'assert-nullability',
    'assume-nonnull',
    'builder',
    'coding',
    'copying',
    'description',
    'equality',
    'fetch-status',
    'immutable-properties',
    'init-new-unavailable',
    'use-cpp',
    'iglistdiffable'
  )
```

--------------------------------

### Objective-C Item Mutations

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Migration.md

Example of how to perform item mutations within a batch block in Objective-C.

```objc
// OLD
self.expanded = YES;
[self.collectionContext insertInSectionController:self atIndexes:[NSIndexSet indexSetWithIndex:]];

// NEW
[self.collectionContext performBatchAnimated:YES updates:^(id<IGListBatchContext> batchContext) {
  self.expanded = YES;
  [batchContext insertInSectionController:self atIndexes:[NSIndexSet indexSetWithIndex:1]];
} completion:nil];
```

--------------------------------

### Customized Initial Layout Attributes

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListCollectionViewDelegateLayout.html

Asks the delegate to customize and return the starting layout information for an item being inserted into the collection view.

```objc
- (UICollectionViewLayoutAttributes *)collectionView:
                                                  (UICollectionView *)collectionView
                                                      layout:(UICollectionViewLayout *) 
                                                                 collectionViewLayout
                           customizedInitialLayoutAttributes:
                               (UICollectionViewLayoutAttributes *)attributes
                                                 atIndexPath:(NSIndexPath *)indexPath;

```

```swift
func collectionView(_ collectionView: UICollectionView!, layout collectionViewLayout: UICollectionViewLayout!, customizedInitialLayoutAttributes attributes: UICollectionViewLayoutAttributes!, at indexPath: IndexPath!) -> UICollectionViewLayoutAttributes!

```

--------------------------------

### UserProvider class for fetching Core Data objects

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Working with Core Data.md

Example of a Provider class using NSFetchedResultsController to fetch Core Data objects and track updates.

```swift
final class UserProvider: NSObject {

    private lazy var userFetchResultController: NSFetchedResultsController<User> = {
        let fetchRequest: NSFetchRequest<User> = NSFetchRequest(entityName: "User")

        // sort descriptors and predicates 
        // ...
    
        let fetchResultController = NSFetchedResultsController(
           fetchRequest: tripsFetchRequest,
           managedObjectContext: self.coreDataStack.mainQueueManagedObjectContext,
           sectionNameKeyPath: nil,
           cacheName: nil)

        // Set delegate to track CoreData changes
        fetchResultController.delegate = self

        return fetchResultController
    }()

    init(coreDataStack: CoreDataStack) {
        self.coreDataStack = coreDataStack
        super.init()
        do {
            try userFetchResultController.performFetch()
        }
        catch {
            fatalError("Cannot Fetch! \(error)")
        }
    }
}
```

--------------------------------

### IGListDiffable Conformance (Objective-C)

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Migration.md

Example of conforming to IGListDiffable in Objective-C to maintain previous behavior.

```objc
#import <IGListDiffKit/IGListDiffable.h>

// Header
@interface MyModel <IGListDiffable>

// Implementation
- (id<NSObject>)diffIdentifier {
  return self;
}

- (BOOL)isEqualToDiffableObject:(id<IGListDiffable>)object {
  return [self isEqual:object];
}
```

--------------------------------

### Objective-C Equality Check

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListBindingSectionController.html

Example of how to implement -isEqualToDiffableObject: in Objective-C for IGListBindingSectionController.

```Objective-C
- (BOOL)isEqualToDiffableObject:(id)object {
  return YES;
}
```

--------------------------------

### Customized Initial Layout Attributes

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListTransitionDelegate.html

Asks the delegate to customize and return the starting layout information for an item being inserted into the collection view.

```objc
- (UICollectionViewLayoutAttributes *)listAdapter:(IGListAdapter *)listAdapter
                        customizedInitialLayoutAttributes:
                            (UICollectionViewLayoutAttributes *)attributes
                                        sectionController:
                                            (IGListSectionController *)sectionController
                                                  atIndex:(NSInteger)index;
```

```swift
func listAdapter(_ listAdapter: Any!, customizedInitialLayoutAttributes attributes: Any!, sectionController: Any!, atIndex index: Any!) -> Any!
```

--------------------------------

### Swift Equality Check

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListBindingSectionController.html

Example of how to implement isEqual(toDiffableObject:) in Swift for ListBindingSectionController.

```Swift
func isEqual(toDiffableObject object: IGListDiffable?) -> Bool {
  return true
}
```

--------------------------------

### Swift Package Manager Installation

Source: https://github.com/instagram/iglistkit/blob/main/README.md

For Swift Package Manager, you can integrate using Xcode by going to File -> Swift Packages -> Add Package Dependency and entering the package URL: https://github.com/Instagram/IGListKit, then selecting the latest release.

```swift
https://github.com/Instagram/IGListKit
```

--------------------------------

### UserProvider with NSFetchedResultsController

Source: https://github.com/instagram/iglistkit/blob/main/docs/working-with-core-data.html

An example of a UserProvider class using NSFetchedResultsController to fetch Core Data objects and track updates.

```swift
final class UserProvider: NSObject {

    private lazy var userFetchResultController: NSFetchedResultsController<User> = {
        let fetchRequest: NSFetchRequest<User> = NSFetchRequest(entityName: "User")

        // sort descriptors and predicates 
        // ...

        let fetchResultController = NSFetchedResultsController(
           fetchRequest: tripsFetchRequest,
           managedObjectContext: self.coreDataStack.mainQueueManagedObjectContext,
           sectionNameKeyPath: nil,
           cacheName: nil)

        // Set delegate to track CoreData changes
        fetchResultController.delegate = self

        return fetchResultController
    }()

    init(coreDataStack: CoreDataStack) {
        self.coreDataStack = coreDataStack
        super.init()
        do {
            try userFetchResultController.performFetch()
        }
        catch {
            fatalError("Cannot Fetch! \(error)")
        }
    }
}
```

--------------------------------

### Updating listAdapter delegate method

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Example Swift code to update the listAdapter delegate method to return a PostSectionController.

```swift
func listAdapter(
  _ listAdapter: ListAdapter,
  sectionControllerFor object: Any
  ) -> ListSectionController {
  return PostSectionController()
}

```

--------------------------------

### User Class Implementation

Source: https://github.com/instagram/iglistkit/blob/main/docs/iglistdiffable-and-equality.html

Example implementation of the User class conforming to IGListDiffable, including diffIdentifier, isEqualToDiffableObject, and isEqual methods.

```Objective-C
@interface User <IGListDiffable>

// properties...

@end

@implementation User

- (id<NSObject>)diffIdentifier {
    return @(self.identifier);
}

- (BOOL)isEqualToDiffableObject:(id<IGListDiffable>)object {
    return [self isEqual:object];
}

- (BOOL)isEqual:(id)object {
  if (self == object) {
      return YES;
  }

  if (![object isKindOfClass:[User class]]) {
      return NO;
  }

  User *right = object;
  return self.identifier == right.identifier 
      && (self.name == right.name || [self.name isEqual:right.name])
      && (self.posts == right.posts || [self.posts isEqualToArray:right.posts]);
}

@end
```

--------------------------------

### Swift didUpdateToObject

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Best Practices and FAQ.md

Example of adding a precondition to check the object type in didUpdateToObject for Swift.

```swift
// Swift
func didUpdate(to object: Any) {
    precondition(object is MyModelClass)
    myModel = object as! MyModelClass
}
```

--------------------------------

### IGListDiffable Conformance - Swift

Source: https://github.com/instagram/iglistkit/blob/main/docs/migration.html

Example of conforming a model to the ListDiffable protocol in Swift, replicating 1.0 behavior.

```swift
import IGListKit

extension MyModel: ListDiffable {
  func diffIdentifier() -> NSObjectProtocol {
    return self
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    return isEqual(object)
  }
}

```

--------------------------------

### Objective-C didUpdateToObject

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Best Practices and FAQ.md

Example of adding an assert to check the object type in didUpdateToObject for Objective-C.

```objective-c
// Objective-C
- (void)didUpdateToObject:(id)object {
    NSParameterAssert([object isKindOfClass:[MyModelClass class]]);
    _myModel = object;
}
```

--------------------------------

### Swift Package Manager Installation (Xcode)

Source: https://github.com/instagram/iglistkit/blob/main/docs/index.html

Integrate IGListKit using Swift Package Manager via Xcode by adding the package dependency.

```swift
File -> Swift Packages -> Add Package Dependency

Enter package URL: https://github.com/Instagram/IGListKit, and select the latest release.
```

--------------------------------

### listAdapter:didEndDisplayingObject:cell:atIndexPath:

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListAdapterDelegate.html

Notifies the delegate that a list object is no longer being displayed. This method is distinct from didEndDisplayingObject:atIndex because this method gets called whenever a cell ends display on screen as opposed to didEndDisplayingObject:atIndex which only gets called once when the section fully ends display.

```objc
- (void)listAdapter:(nonnull IGListAdapter *)listAdapter
            didEndDisplayingObject:(nonnull id)object
                              cell:(nonnull UICollectionViewCell *)cell
                       atIndexPath:(nonnull NSIndexPath *)indexPath;
```

```swift
func listAdapter(_ listAdapter: IGListAdapter, didEndDisplaying object: Any, cell: UICollectionViewCell, at indexPath: IndexPath)
```

--------------------------------

### PostSectionController ActionViewModel Initialization

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Initializes ActionViewModel with localLikes if available, otherwise with object.likes.

```swift
ActionViewModel(likes: localLikes ?? object.likes)
```

--------------------------------

### ImageViewModel and ActionViewModel Implementations

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Implementations for ImageViewModel and ActionViewModel.

```swift
import IGListKit

final class ImageViewModel: ListDiffable {
  let url: URL

  init(url: URL) {
    self.url = url
  }

  // MARK: ListDiffable

  func diffIdentifier() -> NSObjectProtocol {
    return "image" as NSObjectProtocol
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    guard let object = object as? ImageViewModel else {
      return false
    }
    return url == object.url
  }
}

final class ActionViewModel: ListDiffable {
  let likes: Int

  init(likes: Int) {
    self.likes = likes
  }

  // MARK: ListDiffable

  func diffIdentifier() -> NSObjectProtocol {
    return "action" as NSObjectProtocol
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    guard let object = object as? ActionViewModel else {
      return false
    }
    return likes == object.likes
  }
}
```

--------------------------------

### Initializer with Nib Name

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListSingleSectionController.html

Initializes a new section controller using a nib file for the cell.

```Objective-C
- (nonnull instancetype)initWithNibName:(nullable NSString *)nibName
                 bundle:(nullable NSBundle *)bundle
         configureBlock:
             (nonnull IGListSingleSectionCellConfigureBlock)configureBlock
              sizeBlock:(nonnull IGListSingleSectionCellSizeBlock)sizeBlock;
```

```Swift
init(nibName: String, bundle: Bundle?, configureBlock: @escaping ListSingleSectionCellConfigureBlock, sizeBlock: @escaping ListSingleSectionCellSizeBlock)
```

--------------------------------

### ImageViewModel and ActionViewModel Implementations

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Implementations for ImageViewModel and ActionViewModel, conforming to ListDiffable.

```swift
import IGListKit

final class ImageViewModel: ListDiffable {

  let url: URL

  init(url: URL) {
    self.url = url
  }

  // MARK: ListDiffable

  func diffIdentifier() -> NSObjectProtocol {
    return "image" as NSObjectProtocol
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    guard let object = object as? ImageViewModel else { return false }
    return url == object.url
  }

}

final class ActionViewModel: ListDiffable {

  let likes: Int

  init(likes: Int) {
    self.likes = likes
  }

  // MARK: ListDiffable

  func diffIdentifier() -> NSObjectProtocol {
    return "action" as NSObjectProtocol
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    guard let object = object as? ActionViewModel else { return false }
    return likes == object.likes
  }
  
}
```

--------------------------------

### Swift oldIndexPathForIdentifier: Method

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListIndexPathResult.html

Swift method to get the old index path for an identifier.

```swift
func oldIndexPath(forIdentifier identifier: any NSObjectProtocol) -> IndexPath?
```

--------------------------------

### initWithUpdater:viewController:workingRangeSize:

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListAdapter.html

Initializes a new IGListAdapter object.

```Objective-C
- (nonnull instancetype)
             initWithUpdater:(nonnull id<IGListUpdatingDelegate>)updater
              viewController:(nullable UIViewController *)viewController
            workingRangeSize:(NSInteger)workingRangeSize;
```

```Swift
init(updater: any IGListUpdatingDelegate, viewController: UIViewController?, workingRangeSize: Int)
```

--------------------------------

### Objective-C oldIndexPathForIdentifier: Method

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListIndexPathResult.html

Objective-C method to get the old index path for an identifier.

```objc
- (nullable NSIndexPath *)oldIndexPathForIdentifier:
            (nonnull id<NSObject>)identifier;
```

--------------------------------

### IGListTransitionData init Objective-C

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListTransitionData.html

Unavailable Objective-C initializer for IGListTransitionData.

```objc
- (instancetype)init NS_UNAVAILABLE;
```

--------------------------------

### Size for each view model

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Implementation of the sectionController(_:sizeForViewModel:at:) method to determine the appropriate size for each view model.

```swift
func sectionController(
  _ sectionController: ListBindingSectionController<ListDiffable>,
  sizeForViewModel viewModel: Any,
  at index: Int
  ) -> CGSize {
  // 1
  guard let width = collectionContext?.containerSize.width else { fatalError() }
  // 2
  let height: CGFloat
  switch viewModel {
  case is ImageViewModel: height = 250
  case is Comment: height = 35
  // 3
  default: height = 55
  }
  return CGSize(width: width, height: height)
}
```

--------------------------------

### Swift Method Signature

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListCollectionViewDelegateLayout.html

The Swift method signature for customizing layout attributes.

```Swift
func collectionView(_ collectionView: UICollectionView!, layout collectionViewLayout: UICollectionViewLayout!, customizedFinalLayoutAttributes attributes: UICollectionViewLayoutAttributes!, at indexPath: IndexPath!) -> UICollectionViewLayoutAttributes!
```

--------------------------------

### configureCell:withViewModel: Declaration

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListBindingSingleSectionController.html

Declaration for the configureCell:withViewModel: method in Objective-C and Swift.

```Objective-C
- (void)configureCell:(Cell)cell withViewModel:(ViewModel)viewModel;
```

```Swift
func configureCell(_ cell: Cell, withViewModel viewModel: ViewModel)
```

--------------------------------

### Objective-C initWithNibName:bundle:configureBlock:sizeBlock:

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListSingleSectionController.html

Creates a new section controller for a given nib name and bundle that will always have only one cell when present in a list.

```objc
- (nonnull instancetype)
            initWithNibName:(nonnull NSString *)nibName
```

--------------------------------

### Declaration of emptyView(for:)

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListAdapterDataSource.html

This snippet shows the Objective-C and Swift declarations for the emptyView(for:) method, which is called by the list adapter to get a background view.

```Objective-C
- (nullable UIView *)emptyViewForListAdapter:
    (nonnull IGListAdapter *)listAdapter;
```

```Swift
func emptyView(for listAdapter: IGListAdapter) -> UIView?
```

--------------------------------

### Swift Initialization

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListSingleSectionController.html

Creates a new section controller for a given cell type that will always have only one cell when present in a list.

```swift
class ListSingleSectionController : ListSectionController
```

--------------------------------

### Type Checking in didUpdateToObject

Source: https://github.com/instagram/iglistkit/blob/main/docs/best-practices-and-faq.html

Example of adding an assert to check the object type in `didUpdateToObject` within a section controller to catch easily-overlooked mistakes in the `IGListAdapterDataSource` implementation.

```Objective-C
- (void)didUpdateToObject:(id)object {
    NSParameterAssert([object isKindOfClass:[MyModelClass class]]);
    _myModel = object;
}
```

```Swift
func didUpdate(to object: Any) {
    precondition(object is MyModelClass)
    myModel = object as! MyModelClass
}
```

--------------------------------

### Wrapper Model Diffable Conformance

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Best Practices and FAQ.md

Making a wrapper model diffable by conforming to ListDiffable.

```swift
extension WeatherSectionModel: ListDiffable {
  func diffIdentifier() -> NSObjectProtocol {
    return location.identifier
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    guard self !== object else { return true }
    guard let object = object as? WeatherSectionModel else { return false }
    return location == object.location && forecast == object.forecast && conditions == object.conditions
  }
}
```

--------------------------------

### initWithStickyHeaders:scrollDirection:topContentInset:stretchToEdge:

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListCollectionViewLayout.html

Create and return a new collection view layout.

```Objective-C
- (nonnull instancetype)
            initWithStickyHeaders:(BOOL)stickyHeaders
                  scrollDirection:(UICollectionViewScrollDirection)scrollDirection
                  topContentInset:(CGFloat)topContentInset
                    stretchToEdge:(BOOL)stretchToEdge;
```

```Swift
init(stickyHeaders: Bool, scrollDirection: UICollectionView.ScrollDirection, topContentInset: CGFloat, stretchToEdge: Bool)
```

--------------------------------

### offsetForFirstVisibleItemWithScrollDirection:

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListAdapter.html

Gets the scroll offset of the first visible cell scrolled into in the collection view. This refers to the cell currently at the top/left (0, 0) of the collection view’s frame, inset by the collection view’s contentInset top or left value if defined.

```Objective-C
- (CGFloat)offsetForFirstVisibleItemWithScrollDirection:
            (UICollectionViewScrollDirection)scrollDirection;
```

```Swift
func offsetForFirstVisibleItem(with scrollDirection: UICollectionView.ScrollDirection) -> CGFloat
```

--------------------------------

### Using both IGListDiffable and -isEqual:

Source: https://github.com/instagram/iglistkit/blob/main/Guides/IGListDiffable and Equality.md

Making objects work universally with Objective-C containers and IGListKit by implementing -isEqual: and -hash.

```objc
@interface User <IGListDiffable>

// properties...

@end

@implementation User

- (id<NSObject>)diffIdentifier {
    return @(self.identifier);
}

- (BOOL)isEqualToDiffableObject:(id<IGListDiffable>)object {
    return [self isEqual:object];
}

@end
```

--------------------------------

### UserViewModel Implementation

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Implementation of the UserViewModel for the UserCell.

```swift
import IGListKit

final class UserViewModel: ListDiffable {

  let username: String
  let timestamp: String

  init(username: String, timestamp: String) {
    self.username = username
    self.timestamp = timestamp
  }

  // MARK: ListDiffable

  func diffIdentifier() -> NSObjectProtocol {
    // 1
    return "user" as NSObjectProtocol
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    // 2
    guard let object = object as? UserViewModel else  { return false }
    return username == object.username
    && timestamp == object.timestamp
  }

}
```

--------------------------------

### Comment Model Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Implementation of the Comment model conforming to ListDiffable.

```swift
import IGListKit

final class Comment: ListDiffable {

    let username: String
    let text: String

    init(username: String, text: String) {
        self.username = username
        self.text = text
    }

    // MARK: ListDiffable

    func diffIdentifier() -> NSObjectProtocol {
        return (username + text) as NSObjectProtocol
    }

    func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
        return true
    }

}
```

--------------------------------

### supportedElementKinds Method

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListSupplementaryViewSource.html

Asks the SupplementaryViewSource for an array of supported element kinds.

```objc
- (nonnull NSArray<NSString *> *)supportedElementKinds;
```

```swift
func supportedElementKinds() -> [String]
```

--------------------------------

### Initializer with Storyboard Cell Identifier

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListSingleSectionController.html

Creates a new section controller for a given storyboard cell identifier.

```Objective-C
- (nonnull instancetype)
    initWithStoryboardCellIdentifier:(nonnull NSString *)identifier
                      configureBlock:
                          (nonnull IGListSingleSectionCellConfigureBlock)
                              configureBlock
                           sizeBlock:(nonnull IGListSingleSectionCellSizeBlock)
                                         sizeBlock;
```

```Swift
init(storyboardCellIdentifier identifier: String, configureBlock: @escaping ListSingleSectionCellConfigureBlock, sizeBlock: @escaping ListSingleSectionCellSizeBlock)
```

--------------------------------

### Comment Model Implementation

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Implementation of the Comment model conforming to ListDiffable.

```swift
import IGListKit

final class Comment: ListDiffable {
  let username: String
  let text: String

  init(username: String, text: String) {
    self.username = username
    self.text = text
  }

  // MARK: ListDiffable

  func diffIdentifier() -> NSObjectProtocol {
    return (username + text) as NSObjectProtocol
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    return true
  }
}
```

--------------------------------

### initWithStickyHeaders:topContentInset:stretchToEdge:

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListCollectionViewLayout.html

Create and return a new vertically scrolling collection view layout.

```Objective-C
- (nonnull instancetype)initWithStickyHeaders:(BOOL)stickyHeaders
                                      topContentInset:(CGFloat)topContentInset
                                        stretchToEdge:(BOOL)stretchToEdge;
```

```Swift
convenience init(stickyHeaders: Bool, topContentInset: CGFloat, stretchToEdge: Bool)
```

--------------------------------

### initWithUpdater:viewController:

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListAdapter.html

Initializes a new IGListAdapter object with a working range of 0.

```Objective-C
- (nonnull instancetype)
            initWithUpdater:(nonnull id<IGListUpdatingDelegate>)updater
             viewController:(nullable UIViewController *)viewController;
```

```Swift
convenience init(updater: any IGListUpdatingDelegate, viewController: UIViewController?)
```

--------------------------------

### Declaration

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListBindingSectionControllerDataSource.html

The declaration of the sizeForViewModel method in both Objective-C and Swift.

```objective-c
- (CGSize)sectionController: (nonnull IGListBindingSectionController *)sectionController sizeForViewModel:(nonnull id)viewModel atIndex:(NSInteger)index;
```

```swift
func sectionController(_ sectionController: IGListBindingSectionController, sizeForViewModel viewModel: Any, at index: Int) -> CGSize
```

--------------------------------

### Objective-C Initialization

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListSingleSectionController.html

Creates a new section controller for a given cell type that will always have only one cell when present in a list.

```objc
@interface IGListSingleSectionController : IGListSectionController
```

--------------------------------

### IGListTransitionData initFromObjects:toObjects:toSectionControllers: Swift

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListTransitionData.html

Swift initializer for ListTransitionData.

```swift
init(from fromObjects: [Any], to toObjects: [Any], to toSectionControllers: [IGListSectionController])
```

--------------------------------

### PostSectionController ActionCellDelegate Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Provides an empty implementation for the ActionCellDelegate protocol in PostSectionController.

```swift
final class PostSectionController:
ListBindingSectionController<Post>,
ListBindingSectionControllerDataSource,
ActionCellDelegate {

//...

// MARK: ActionCellDelegate

func didTapHeart(cell: ActionCell) {
  print("like")
}
}
```

--------------------------------

### ListDiffable Implementation for Post

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Implements the ListDiffable protocol for the Post model, providing a unique identifier and equality check.

```swift
// MARK: ListDiffable

func diffIdentifier() -> NSObjectProtocol {
  // 1
  return (username + timestamp) as NSObjectProtocol
}

// 2
func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
  return true
}
```

--------------------------------

### Swift Class

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListBindingSingleSectionController.html

Swift class definition for IGListBindingSingleSectionController.

```swift
class ListBindingSingleSectionController<ViewModel, Cell> : ListSectionController where ViewModel : ListDiffable, Cell : UICollectionViewCell
```

--------------------------------

### UserViewModel Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Implementation of the UserViewModel for a UserCell, conforming to ListDiffable.

```swift
import IGListKit

final class UserViewModel: ListDiffable {

  let username: String
  let timestamp: String

  init(username: String, timestamp: String) {
    self.username = username
    self.timestamp = timestamp
  }

  // MARK: ListDiffable

  func diffIdentifier() -> NSObjectProtocol {
    // 1
    return "user" as NSObjectProtocol
  }

  func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
    // 2
    guard let object = object as? UserViewModel  else  { return false }
    return username == object.username
    && timestamp == object.timestamp
  }

}
```

--------------------------------

### Generated PersonModel.m file

Source: https://github.com/instagram/iglistkit/blob/main/docs/generating-your-models-using-remodel.html

The Objective-C implementation file for PersonModel, including initializers, diffIdentifier, equality, copyWithZone, description, and hash methods.

```objective-c
@implementation PersonModel

- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName uniqueId:(NSString *)uniqueId
{
  if ((self = [super init])) {
    _firstName = [firstName copy];
    _lastName = [lastName copy];
    _uniqueId = [uniqueId copy];
  }

  return self;
}

- (id<NSObject>)diffIdentifier
{
  return _uniqueId;
}

- (BOOL)isEqualToDiffableObject:(nullable id<IGListDiffable>)object
{
  return [self isEqual:object];
}

- (BOOL)isEqual:(PersonModel *)object
{
  if (self == object) {
    return YES;
  } else if (self == nil || object == nil || ![object isKindOfClass:[self class]]) {
    return NO;
  }
  return
    (_firstName == object->_firstName ? YES : [_firstName isEqual:object->_firstName]) &&
    (_lastName == object->_lastName ? YES : [_lastName isEqual:object->_lastName]) &&
    (_uniqueId == object->_uniqueId ? YES : [_uniqueId isEqual:object->_uniqueId]);
}

- (id)copyWithZone:(nullable NSZone *)zone
{
  return self;
}

- (NSString *)description
{
  return [NSString stringWithFormat:@"%@ - \n\t firstName: %@; \n\t lastName: %@; \n\t uniqueId: %@; \n", [super description], _firstName, _lastName, _uniqueId];
}

- (NSUInteger)hash
{
  NSUInteger subhashes[] = {[_firstName hash], [_lastName hash], [_uniqueId hash]};
  NSUInteger result = subhashes[0];
  for (int ii = 1; ii < 3; ++ii) {
    unsigned long long base = (((unsigned long long)result) << 32 | subhashes[ii]);
    base = (~base) + (base << 18);
    base ^= (base >> 31);
    base *=  21;
    base ^= (base >> 11);
    base += (base << 6);
    base ^= (base >> 22);
    result = base;
  }
  return result;
}

@end
```

--------------------------------

### Post Model

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Defines the data structure for a post, including username, timestamp, image URL, likes, and comments.

```swift
import IGListKit

final class Post: ListDiffable {

  // 1
  let username: String
  let timestamp: String
  let imageURL: URL
  let likes: Int
  let comments: [Comment]

  // 2
  init(username: String, timestamp: String, imageURL: URL, likes: Int, comments: [Comment]) {
    self.username = username
    self.timestamp = timestamp
    self.imageURL = imageURL
    self.likes = likes
    self.comments = comments
  }

}
```

--------------------------------

### IGListTransitionData initFromObjects:toObjects:toSectionControllers: Objective-C

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListTransitionData.html

Objective-C initializer for IGListTransitionData.

```objc
- (instancetype)initFromObjects:(NSArray *)fromObjects
                              toObjects:(NSArray *)toObjects
                   toSectionControllers:(NSArray<IGListSectionController *> *)toSectionControllers NS_DESIGNATED_INITIALIZER;
```

--------------------------------

### Swift Declaration for 'from'

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListMoveIndexPath.html

Swift declaration for the 'from' property.

```swift
var from: IndexPath { get }
```

--------------------------------

### objects Method

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListAdapter.html

Returns a copy of all the objects currently driving the adapter.

```Objective-C
- (nonnull NSArray *)objects;
```

```Swift
func objects() -> [Any]
```

--------------------------------

### Objective-C Method Signature

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListCollectionViewDelegateLayout.html

The Objective-C method signature for customizing layout attributes.

```Objective-C
(UICollectionViewLayoutAttributes *)attributes
                                atIndexPath:(NSIndexPath *)indexPath;
```

--------------------------------

### Helper method to translate Core Data objects into ViewModel objects

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Working with Core Data.md

Helper method to translate Core Data objects into ViewModel objects.

```swift
extension UserViewModel {
    static func fromCoreData(user: User) -> UserViewModel {
        // - Note: For avoiding Core Data threading violation, the following code should be wrapped in a
        // user.managedObjectContext?.performAndWait {}
        return UserViewModel(firstName: user.firstName, lastName: user.lastName, address: user.lastName)
    }
}
```

--------------------------------

### Objective-C Interface

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListBindingSingleSectionController.html

Objective-C interface for IGListBindingSingleSectionController.

```objc
@interface IGListBindingSingleSectionController<\
    __covariant ViewModel : id <IGListDiffable>, Cell : UICollectionViewCell *> \
    : IGListSectionController
```

--------------------------------

### ActionCell awakeFromNib

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Adds a target and action to the likeButton in ActionCell.

```swift
override func awakeFromNib() {
  super.awakeFromNib()
  likeButton.addTarget(self, action: #selector(ActionCell.onHeart), for: .touchUpInside)
}
```

--------------------------------

### viewForSupplementaryElementOfKind:atIndex: Method

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListSupplementaryViewSource.html

Asks the SupplementaryViewSource for a configured supplementary view for the specified kind and index. It's important to dequeue a view from the IGListCollectionContext instead of allocating a new one.

```objc
- (nonnull __kindof UICollectionReusableView *)viewForSupplementaryElementOfKind:(nonnull NSString *)elementKind atIndex:(NSInteger)index;
```

```swift
func viewForSupplementaryElement(ofKind elementKind: String, at index: Int) -> UICollectionReusableView
```

--------------------------------

### objectsForListAdapter:

Source: https://github.com/instagram/iglistkit/blob/main/docs/Protocols/IGListAdapterDataSource.html

Asks the data source for the objects to display in the list.

```objc
- (nonnull NSArray<id<IGListDiffable>> *)objectsForListAdapter:
            (nonnull IGListAdapter *)listAdapter;
```

```swift
func objects(for listAdapter: IGListAdapter) -> [any ListDiffable]
```

--------------------------------

### PostSectionController conforming to ActionCellDelegate

Source: https://github.com/instagram/iglistkit/blob/main/docs/modeling-and-binding.html

Swift code showing PostSectionController conforming to ActionCellDelegate and implementing didTapHeart.

```swift
final class PostSectionController: ListBindingSectionController<Post>,
ListBindingSectionControllerDataSource,
ActionCellDelegate {

// ...

// MARK: ActionCellDelegate

func didTapHeart(cell: ActionCell) {
  print("like")
}

```

--------------------------------

### showHeaderWhenEmpty

Source: https://github.com/instagram/iglistkit/blob/main/docs/Classes/IGListCollectionViewLayout.html

Set this to `YES` to show sticky header when a section had no item. Default is `NO`.

```Objective-C
@property (nonatomic) BOOL showHeaderWhenEmpty;
```

```Swift
var showHeaderWhenEmpty: Bool { get set }
```

--------------------------------

### Post-to-view-models transformation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Implementation of the sectionController(_:viewModelsFor:) method to transform a Post model into an array of ListDiffable view models.

```swift
// MARK: ListBindingSectionControllerDataSource

func sectionController(
  _ sectionController: ListBindingSectionController<ListDiffable>,
  viewModelsFor object: Any
  ) -> [ListDiffable] {
    // 1
    guard let object = object as? Post else { fatalError() }
    // 2
    let results: [ListDiffable] = [
      UserViewModel(username: object.username, timestamp: object.timestamp),
      ImageViewModel(url: object.imageURL),
      ActionViewModel(likes: object.likes)
    ]
    // 3
    return results + object.comments
}
```

--------------------------------

### ActionCell onHeart Implementation

Source: https://github.com/instagram/iglistkit/blob/main/Guides/Modeling and Binding.md

Implements the onHeart method to forward the button tap to the delegate.

```swift
func onHeart() {
  delegate?.didTapHeart(cell: self)
}
```