### Install Dependencies with CocoaPods

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Contributing

Install necessary testing libraries using CocoaPods before running unit tests.

```bash
pod install
```

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

### Basic Tesseract OCR Integration in Swift

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Using-Tesseract-OCR-iOS

This snippet demonstrates the basic setup for Tesseract OCR in a Swift `ViewController`. It initializes Tesseract with specific languages, sets a delegate, defines a character whitelist, loads an image, and performs recognition. Ensure you have configured an Objective-C bridging header.

```Swift
import UIKit
import TesseractOCR

class ViewController: UIViewController, G8TesseractDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()

        var tesseract:G8Tesseract = G8Tesseract(language:"eng+ita")
        //tesseract.language = "eng+ita"
        tesseract.delegate = self
        tesseract.charWhitelist = "01234567890"
        tesseract.image = UIImage(named: "image_sample.jpg")
        tesseract.recognize()

        print(tesseract.recognizedText)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func shouldCancelImageRecognitionForTesseract(tesseract: G8Tesseract!) -> Bool {
        return false // return true if you need to interrupt tesseract before it finishes
    }
}
```

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

### Install with Carthage

Source: https://github.com/gali8/tesseract-ocr-ios/blob/master/README.md

Add this line to your Cartfile to include the Tesseract OCR iOS framework in your project via Carthage. After adding, run 'carthage update'.

```bash
github "gali8/Tesseract-OCR-iOS"
```

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

### Add Tesseract OCR via CocoaPods (Stable Version)

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Installation

Use this snippet to add the latest stable version of the Tesseract OCR iOS library to your project's Podfile. After adding the line, run 'pod install'.

```ruby
pod 'TesseractOCRiOS', '4.0.0'
```

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

### Objective-C: Basic Tesseract OCR Usage

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Using-Tesseract-OCR-iOS

Demonstrates how to initialize G8Tesseract, set recognition parameters, and perform OCR on an image. Use this for direct, synchronous recognition tasks.

```Objective-C
#import <TesseractOCR/TesseractOCR>
@interface MyViewController : UIViewController <G8TesseractDelegate>
@end
```

```Objective-C
- (void)viewDidLoad
{
    [super viewDidLoad];

    // Languages are used for recognition (e.g. eng, ita, etc.). Tesseract engine
    // will search for the .traineddata language file in the tessdata directory. 
    // For example, specifying "eng+ita" will search for "eng.traineddata" and
    // "ita.traineddata". Cube engine will search for "eng.cube.*" files.
    // See https://github.com/tesseract-ocr/tessdata.

    // Create your G8Tesseract object using the initWithLanguage method:
    G8Tesseract *tesseract = [[G8Tesseract alloc] initWithLanguage:@"eng+ita"];

    // Optionaly: You could specify engine to recognize with. 
    // G8OCREngineModeTesseractOnly by default. It provides more features and faster
    // than Cube engine. See G8Constants.h for more information.
    //tesseract.engineMode = G8OCREngineModeTesseractOnly;

    // Set up the delegate to receive Tesseract's callbacks.
    // self should respond to TesseractDelegate and implement a
    // "- (BOOL)shouldCancelImageRecognitionForTesseract:(G8Tesseract *)tesseract"
    // method to receive a callback to decide whether or not to interrupt
    // Tesseract before it finishes a recognition.
    tesseract.delegate = self;

    // Optional: Limit the character set Tesseract should try to recognize from
    tesseract.charWhitelist = @"0123456789";

    // This is wrapper for common Tesseract variable kG8ParamTesseditCharWhitelist:
    // [tesseract setVariableValue:@"0123456789" forKey:kG8ParamTesseditCharBlacklist];
    // See G8TesseractParameters.h for a complete list of Tesseract variables

    // Optional: Limit the character set Tesseract should not try to recognize from
    //tesseract.charBlacklist = @"OoZzBbSs";

    // Specify the image Tesseract should recognize on
    tesseract.image = [[UIImage imageNamed:@"image_sample.jpg"] g8_blackAndWhite];

    // Optional: Limit the area of the image Tesseract should recognize on to a rectangle
    tesseract.rect = CGRectMake(20, 20, 100, 100);

    // Optional: Limit recognition time with a few seconds
    tesseract.maximumRecognitionTime = 2.0;

    // Start the recognition
    [tesseract recognize];

    // Retrieve the recognized text
    NSLog(@"%@", [tesseract recognizedText]);

    // You could retrieve more information about recognized text with that methods:
    NSArray *characterBoxes = [tesseract recognizedBlocksByIteratorLevel:G8PageIteratorLevelSymbol];
    NSArray *paragraphs = [tesseract recognizedBlocksByIteratorLevel:G8PageIteratorLevelParagraph];
    NSArray *characterChoices = tesseract.characterChoices;
    UIImage *imageWithBlocks = [tesseract imageWithBlocks:characterBoxes drawText:YES thresholded:NO]; 
}

- (void)progressImageRecognitionForTesseract:(G8Tesseract *)tesseract {
    NSLog(@"progress: %lu", (unsigned long)tesseract.progress);
}

- (BOOL)shouldCancelImageRecognitionForTesseract:(G8Tesseract *)tesseract {
    return NO;  // return YES, if you need to interrupt tesseract before it finishes
}

```

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

### Specify Architectures for Build

Source: https://github.com/gali8/tesseract-ocr-ios/blob/master/TesseractOCR/README_howto_compile_libaries.md

Builds Tesseract OCR libraries for specific iOS architectures, useful for AppStore submissions.

```bash
export ARCHS=armv7, armv7s, arm64
```

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

### Initialize Tesseract with Configuration Files

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Advanced-Tesseract-Configuration

Initializes a G8Tesseract object using custom configuration files. This is useful for managing complex or reusable sets of parameters.

```Objective-C
// Construct the paths to our config files
NSString *resourcePath = [NSBundle bundleForClass:G8Tesseract.class].resourcePath;
NSString *tessdataFolderName = @"tessdata";
NSString *tessdataFolderPathFromTheBundle = [[resourcePath stringByAppendingPathComponent:tessdataFolderName] stringByAppendingString:@"/"];
NSString *debugConfigFileName = @"debugConfig.txt";
NSString *recognitionConfigFileName = @"recognitionConfig.txt";
NSString *tessConfigsFolderName = @"tessconfigs";
NSString *debugConfigFilePath = [[tessdataFolderPathFromTheBundle stringByAppendingPathComponent:tessConfigsFolderName]  stringByAppendingPathComponent:debugConfigsFileName];
NSString *recognitionConfigFilePath = [[tessdataFolderPathFromTheBundle stringByAppendingPathComponent:tessConfigsFolderName]  stringByAppendingPathComponent:recognitionConfigsFileName];

// Initialize the `G8Tesseract` object using the config files
G8Tesseract *tesseract = [[G8Tesseract alloc] initWithLanguage:kG8Languages
                                              configDictionary:nil
                                               configFileNames:@[debugConfigFilePath, recognitionConfigFilePath]
                                         cachesRelatedDataPath:nil
                                                    engineMode:G8OCREngineModeTesseractOnly];
```

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

### Objective-C: Asynchronous Tesseract OCR with NSOperationQueue

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Using-Tesseract-OCR-iOS

Shows how to perform Tesseract OCR asynchronously using NSOperationQueue for better performance in the UI thread. Ideal for long-running recognition tasks.

```Objective-C
#import <TesseractOCR/TesseractOCR>
@interface MyViewController : UIViewController
@end
```

```Objective-C
- (void)viewDidLoad
{
    // Create RecognitionOperation
    G8RecognitionOperation *operation = [[G8RecognitionOperation alloc] initWithLanguage:@"eng+ita"];

    // Configure inner G8Tesseract object as described before
    operation.tesseract.charWhitelist = @"01234567890";
    operation.tesseract.image = [[UIImage imageNamed:@"image_sample.jpg"] g8_blackAndWhite];

    // Setup the recognitionCompleteBlock to receive the Tesseract object
    // after text recognition. It will hold the recognized text.
    operation.recognitionCompleteBlock = ^(G8Tesseract *recognizedTesseract) {
        // Retrieve the recognized text upon completion
        NSLog(@"%@", [recognizedTesseract recognizedText]);
    };

    // Add operation to queue
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    [queue addOperation:operation];
}

```

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

### Initialize Tesseract with Configuration Dictionary

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Advanced-Tesseract-Configuration

Initializes a G8Tesseract object with specified language and a configuration dictionary. This method allows setting multiple parameters during initialization.

```Objective-C
// During initialization, set the whitelist to recognize only the numbers 0 through 9
// and disable word dictionaries
G8Tesseract *tesseract = [[G8Tesseract alloc] initWithLanguage:@"eng"
                                              configDictionary:@{
                                                                kG8ParamTesseditCharWhitelist: @"0123456789",
                                                                kG8ParamLoadSystemDawg       : @"F",
                                                                kG8ParamLoadFreqDawg         : @"F",
                                                                }
                                              configFileNames:nil
                                              cachesRelatedDataPath:nil
                                              engineMode:G8OCREngineModeTesseractOnly];
```

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

### Link libz.dylib or libz.tbd in Xcode

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Installation

Manually link the libz library to your target in Xcode's 'Build Phases' if it's not automatically included. This is a necessary step for the Tesseract OCR framework.

```bash
-lz
```

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

### Initialize G8Tesseract with Custom Tessdata Path

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Advanced-Tesseract-Configuration

Use this Objective-C snippet to initialize `G8Tesseract` with a custom path relative to the Caches directory for the 'tessdata' folder. This allows for runtime downloads of language and configuration files.

```Objective-C
G8Tesseract *tesseract = [[G8Tesseract alloc] initWithLanguage:@"eng"
                                              configDictionary:nil
                                               configFileNames:nil
                                         cachesRelatedDataPath:@"foo/bar"
                                                    engineMode:G8OCREngineModeTesseractOnly];
```

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

### Build Tesseract OCR Libraries

Source: https://github.com/gali8/tesseract-ocr-ios/blob/master/TesseractOCR/README_howto_compile_libaries.md

Compiles dependent libraries and Tesseract for all iOS architectures (device and simulator).

```bash
make
```

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

### Clone Tesseract-OCR-iOS Repository

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Contributing

Clone your forked repository from GitHub to your local machine to begin making changes.

```bash
git clone git@github.com:username/Tesseract-OCR-iOS.git
```

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

### Using GPUImage Adaptive Threshold Filter for OCR

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Tips for Improving OCR Results

Preprocess an image using GPUImage's adaptive threshold filter before passing it to Tesseract. Adjust 'blurRadiusInPixels' to fine-tune the filter.

```Objective-C
// Grab the image you want to preprocess
UIImage *inputImage = [UIImage imageNamed:@"my_test_image.jpg"];

// Initialize our adaptive threshold filter
GPUImageAdaptiveThresholdFilter *stillImageFilter = [[GPUImageAdaptiveThresholdFilter alloc] init];
stillImageFilter.blurRadiusInPixels = 4.0 // adjust this to tweak the blur radius of the filter, defaults to 4.0

// Retrieve the filtered image from the filter
UIImage *filteredImage = [stillImageFilter imageByFilteringImage:inputImage];

// Give Tesseract the filtered image
tesseract.image = filteredImage;
```

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

### Add Tesseract OCR via CocoaPods (Development Version)

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Installation

Integrate the development version of the Tesseract OCR iOS library from its GitHub repository. Ensure you only have one 'TesseractOCRiOS' line in your Podfile. This uses the master branch and is not based on a stable release.

```ruby
pod 'TesseractOCRiOS', :git => 'https://github.com/gali8/Tesseract-OCR-iOS.git'
```

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

### Import TesseractOCR in Swift Class

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Installation

Remember to import the TesseractOCR module at the top of your Swift class file to use its functionalities.

```swift
import TesseractOCR
```

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

### Bypassing Tesseract's Internal Thresholder with Delegate

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Tips for Improving OCR Results

Implement the Tesseract delegate method 'preprocessedImageForTesseract:sourceImage:' to bypass Tesseract's internal thresholding when custom preprocessing is applied. This method should return the preprocessed image.

```Objective-C
// somewhere in the function of your class
// set the delegate
tesseract.delegate = self;
// give the original, non-processed image to Tesseract
tesseract.image = [UIImage imageNamed:@"my_test_image.jpg"];

// Tesseract delegate method inside of your class
- (UIImage *)preprocessedImageForTesseract:(G8Tesseract *)tesseract sourceImage:(UIImage *)sourceImage {

    // sourceImage is the same image you sent to Tesseract above
    UIImage *inputImage = sourceImage;

    // Initialize our adaptive threshold filter
    GPUImageAdaptiveThresholdFilter *stillImageFilter = [[GPUImageAdaptiveThresholdFilter alloc] init];
    stillImageFilter.blurRadiusInPixels = 4.0 // adjust this to tweak the blur radius of the filter, defaults to 4.0

    // Retrieve the filtered image from the filter
    UIImage *filteredImage = [stillImageFilter imageByFilteringImage:inputImage];

    // Give the filteredImage to Tesseract instead of the original one, 
    // allowing us to bypass the internal thresholding step.
    // filteredImage will be sent immediately to the recognition step
    return filteredImage;
}
```

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

### Set GENERATE_MASTER_OBJECT_FILE to YES

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Installation

Resolve runtime errors like 'unrecognized selector sent to instance' by setting 'GENERATE_MASTER_OBJECT_FILE' to 'YES' in the Tesseract OCR iOS.xcodeproj build settings. This may increase the executable file size.

```bash
GENERATE_MASTER_OBJECT_FILE = YES
```

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

### Read Tesseract Parameter Value

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Advanced-Tesseract-Configuration

Reads the value of a specific Tesseract parameter using its key. Useful for inspecting current settings.

```Objective-C
// Assuming "tesseract" is an already initialized `G8Tesseract` object
NSString *whitelist = [tesseract variableValueForKey:kG8ParamTesseditCharWhitelist];
```

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

### Add -lstdc++ to Other Linker Flags

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Installation

Include '-lstdc++' in your project's 'Other Linker Flags' to prevent a multitude of build errors during the linking phase.

```bash
-lstdc++
```

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

### Clearing Tesseract Instance

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Release-Notes

Deprecated method for clearing Tesseract instance. Use `tesseract = nil;` to free memory.

```Objective-C
[tesseract clear]; //call Clear() end End() functions
```

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

### Set Tesseract Parameter Individually

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Advanced-Tesseract-Configuration

Sets a single Tesseract parameter value after the Tesseract object has been initialized. This method is straightforward for modifying one parameter at a time.

```Objective-C
// Assuming "tesseract" is an already initialized `G8Tesseract` object
// Set the whitelist to recognize only the numbers 0 through 9
[tesseract setVariableValue:@"0123456789" forKey:kG8ParamTesseditCharWhitelist];
```

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

### Disable Bitcode for Swift (iOS 9 & 10)

Source: https://github.com/gali8/tesseract-ocr-ios/wiki/Installation

For Swift projects targeting iOS 9 and iOS 10, disable Bitcode in your target's build settings. This is also required for the Tesseract OCR POD's bitcode.

```bash
ENABLE_BITCODE = NO
```

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