### Custom Decoder Engine Implementation

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Architecture.md

Provides an example of how to implement a custom decoder engine by conforming to the AppReceiptDecoder.Engine protocol. This allows for custom parsing logic when decoding receipt data.

```swift
struct MyEngine: AppReceiptDecoder.Engine {
    func decode(from data: Data) throws -> AppReceipt {
        // custom parsing
    }
}

let decoder = AppReceiptDecoder(engine: MyEngine())
let receipt = try decoder.decode(from: data)
```

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

### Decoding Receipt

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Provides examples for decoding App Store receipt data, both from a local file and from raw data.

```APIDOC
## Decoding Receipt

```swift
import TPInAppReceipt

// Local receipt
let receipt = try await AppReceipt.local

// From raw data
let receipt = try AppReceipt.receipt(from: data)
```

`AppReceipt` is a typealias over `ContentInfo<SignedData<InAppReceiptPayload>>` — the full PKCS#7 structure is accessible.
```

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

### Introductory Offer Eligibility

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Explains how to check if a user is eligible for an introductory offer for a given subscription group.

```APIDOC
## Introductory Offer Eligibility

Pass product identifiers within the same subscription group:

```swift
receipt.isEligibleForIntroductoryOffer(
    for: ["com.example.bronze", "com.example.silver", "com.example.gold"]
)
```
```

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

### Checking Introductory Offer Eligibility

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Determine if a user is eligible for an introductory offer for a given subscription group. Pass an array of product identifiers belonging to the same group.

```swift
receipt.isEligibleForIntroductoryOffer(
    for: ["com.example.bronze", "com.example.silver", "com.example.gold"]
)
```

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

### Format Code with Swift Format

Source: https://github.com/tikhop/tpinappreceipt/blob/master/CONTRIBUTING.md

Use this command to format all Swift files recursively according to the project's .swift-format guidelines. Ensure code is reasonably short and uses meaningful names.

```bash
swift format -i . --recursive
```

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

### Run Project Tests

Source: https://github.com/tikhop/tpinappreceipt/blob/master/CONTRIBUTING.md

Execute all project tests using this command. Ensure all tests pass before submitting contributions.

```bash
swift test
```

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

### Update Receipt Initialization

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/TPInAppReceipt 4.0 Migration Guide.md

Migrate from the old `InAppReceipt` initialization to the new `AppReceipt` async initialization.

```swift
// Before
let receipt = try InAppReceipt.localReceipt()
// or
let receipt = try InAppReceipt()

// After
let receipt = try await AppReceipt.local
```

```swift
// Before
let receipt = try InAppReceipt.receipt(from: data)

// After
let receipt = try AppReceipt.receipt(from: data)
```

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

### Add TPInAppReceipt via Swift Package Manager

Source: https://github.com/tikhop/tpinappreceipt/blob/master/README.md

Add the TPInAppReceipt library to your project using Swift Package Manager. Ensure your target includes the library as a dependency.

```swift
dependencies: [
    .package(url: "https://github.com/tikhop/TPInAppReceipt.git", from: "4.0.2")
]
```

```swift
.target(
    name: "YourTarget",
    dependencies: ["TPInAppReceipt"])

```

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

### Read Local or Raw Data Receipt in Swift

Source: https://github.com/tikhop/tpinappreceipt/blob/master/README.md

Import the TPInAppReceipt library to access receipt data. Use `AppReceipt.local` for the local receipt or `AppReceipt.receipt(from: data)` for raw data.

```swift
import TPInAppReceipt

// Local receipt
let receipt = try await AppReceipt.local

// From raw data
let receipt = try AppReceipt.receipt(from: data)
```

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

### Custom Verifier Implementation

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Architecture.md

Demonstrates how to implement a custom receipt verifier by conforming to the ReceiptVerifier protocol. This allows for custom validation logic to be added to the receipt validation process.

```swift
struct MyVerifier: ReceiptVerifier {
    func verify(_ receipt: ReceiptValidatable) async -> VerificationResult {
        // custom check
        return .valid
    }
}

let validator = ReceiptValidator {
    X509ChainVerifier(rootCertificates: [rootCert])
    MyVerifier()
}
```

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

### Managing Purchases

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Shows how to access and query purchase information from the receipt, including all purchases, auto-renewable subscriptions, and active subscriptions.

```APIDOC
## Managing Purchases

```swift
receipt.purchases              // [InAppPurchase]
receipt.hasPurchases
receipt.autoRenewablePurchases
receipt.activeAutoRenewableSubscriptionPurchases
```

Query by product:

```swift
receipt.purchases(ofProductIdentifier: "com.example.sub")
receipt.containsPurchase(ofProductIdentifier: "com.example.premium")

receipt.hasActiveAutoRenewableSubscription(
    ofProductIdentifier: "com.example.sub",
    forDate: Date()
)

receipt.lastAutoRenewableSubscriptionPurchase(
    ofProductIdentifier: "com.example.sub"
)
```
```

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

### Querying Purchases by Product Identifier

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Filter purchases by their product identifiers. This is useful for checking specific subscriptions or in-app purchases.

```swift
receipt.purchases(ofProductIdentifier: "com.example.sub")
receipt.containsPurchase(ofProductIdentifier: "com.example.premium")

receipt.hasActiveAutoRenewableSubscription(
    ofProductIdentifier: "com.example.sub",
    forDate: Date()
)

receipt.lastAutoRenewableSubscriptionPurchase(
    ofProductIdentifier: "com.example.sub"
)
```

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

### Reading Receipt Properties

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Demonstrates how to access various properties of the decoded receipt, such as bundle identifier, app version, environment, and dates.

```APIDOC
## Reading Receipt Properties

```swift
receipt.bundleIdentifier
receipt.appVersion
receipt.originalAppVersion   // String?
receipt.environment          // .production, .sandbox, .xcode, .productionSandbox
receipt.creationDate
receipt.expirationDate       // VPP only
```

See <doc:Receipt-Fields> for the full list of fields.
```

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

### Accessing Purchase Information

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Retrieve lists of purchases, check for the existence of purchases, and filter auto-renewable subscriptions. Use these properties to manage user entitlements.

```swift
receipt.purchases              // [InAppPurchase]
receipt.hasPurchases
receipt.autoRenewablePurchases
receipt.activeAutoRenewableSubscriptionPurchases
```

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

### Use Blocking API for Synchronous Operations

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/TPInAppReceipt 4.0 Migration Guide.md

Import TPInAppReceipt with `@_spi(Blocking)` to access synchronous variants of asynchronous receipt loading and validation methods.

```swift
@_spi(Blocking) import TPInAppReceipt

// Load receipt
let receipt = try AppReceipt.local_blocking

// Validate
let result = receipt.validate_blocking()
```

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

### Refreshing Receipt

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Provides instructions on how to request an updated receipt from the App Store.

```APIDOC
## Refreshing Receipt

Request an updated receipt from the App Store:

```swift
try await AppReceipt.refresh()
```
```

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

### Custom Receipt Validation with @VerifierBuilder

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Validating Receipt.md

Create a custom validator by combining different verifiers. This allows for fine-grained control over the validation process. Verifiers run in parallel and will cancel if any one fails.

```swift
let validator = ReceiptValidator {
    X509ChainVerifier(rootCertificates: [rootCert])
    SignatureVerifier()
    HashVerifier(deviceIdentifier: deviceId)
    MetaVerifier(
        appVersionProvider: { Bundle.main.appVersion },
        bundleIdentifierProvider: { Bundle.main.bundleIdentifier }
    )
}

let result = await validator.validate(receipt)
```

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

### Reading Receipt Fields

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Access various fields from the decoded receipt object, such as bundle identifier, app version, and environment. Some fields like expirationDate are only available for VPP.

```swift
receipt.bundleIdentifier
receipt.appVersion
receipt.originalAppVersion   // String?
receipt.environment          // .production, .sandbox, .xcode, .productionSandbox
receipt.creationDate
receipt.expirationDate       // VPP only
```

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

### Validate App Receipt in Blocking Mode

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Blocking Mode.md

Use this snippet to perform synchronous validation of a local app receipt. Ensure the `@_spi(Blocking) import TPInAppReceipt` is included.

```swift
@_spi(Blocking) import TPInAppReceipt

let receipt = try AppReceipt.local_blocking
let result = receipt.validate_blocking()
```

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

### Default Receipt Validation

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Validating Receipt.md

Use this method for a quick and comprehensive validation of the receipt. It automatically selects the correct Apple root certificate.

```swift
let result = await receipt.validate()

switch result {
case .valid:
    break
case .invalid(let error):
    print(error)
}
```

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

### Update Receipt Refresh Mechanism

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/TPInAppReceipt 4.0 Migration Guide.md

Replace the callback-based `InAppReceipt.refresh` with the new `await AppReceipt.refresh()` and utilize Swift Concurrency task cancellation for managing refresh operations.

```swift
// Before
InAppReceipt.refresh { error in
    // ...
}

// After
try await AppReceipt.refresh()
```

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

### Refreshing the App Store Receipt

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Working with Receipt.md

Request an updated receipt from the App Store. This is an asynchronous operation that may require network access.

```swift
try await AppReceipt.refresh()
```

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

### Update Receipt Validation

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/TPInAppReceipt 4.0 Migration Guide.md

Replace the synchronous `receipt.verify()` with the new asynchronous `await receipt.validate()` and handle the `ReceiptValidatorError`.

```swift
// Before
do {
    try receipt.verify()
} catch IARError.validationFailed(reason: .hashValidation) {
    // ...
}

// After
let result = await receipt.validate()
switch result {
case .valid:
    break
case .invalid(let error):
    // error is typed: ReceiptValidatorError, ChainVerificationError, etc.
    print(error)
}
```

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

### AppReceipt Type Alias

Source: https://github.com/tikhop/tpinappreceipt/blob/master/Sources/Docs.docc/Architecture.md

Defines AppReceipt as a type alias for the nested structure of ContentInfo, SignedData, and InAppReceiptPayload.

```swift
public typealias AppReceipt = ContentInfo<SignedData<InAppReceiptPayload>>
```

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