MLKitDigitalInkRecognition Framework Reference

Page Summary

• MLKDigitalInkRecognizer performs handwriting recognition on digital ink, which is a vector representation of user writing composed of strokes and touch points.

• It's initialized using digitalInkRecognizer(options:) with specific options defined in DigitalInkRecognizerOptions.

• Recognition is done through recognizeInk:completion: or recognizeInk:context:completion:, the latter offering better accuracy by using context like writing area size and previously entered text.

• Recognition results are returned via a callback function (DigitalInkRecognizerCallback) with a list of candidate strings.

• Providing context through DigitalInkRecognitionContext can help disambiguate recognition and improve accuracy, especially when building upon previous recognitions.

MLKDigitalInkRecognizer

@interface MLKDigitalInkRecognizer : NSObject

Object to perform handwriting recognition on digital ink.

Digital ink is the vector representation of what a user has written. It is composed of a sequence of strokes, each being a sequence of touch points (coordinates and timestamp). See Ink for details.

• -init

  Unavailable. Use digitalInkRecognizer(options:) instead.

  Declaration

  Objective-C

  - (nonnull instancetype)init;

• +digitalInkRecognizerWithOptions:

  Creates a DigitalInkRecognizer object using the specified options.

  See DigitalInkRecognizerOptions for details.

  Declaration

  Objective-C

  + (nonnull MLKDigitalInkRecognizer *)digitalInkRecognizerWithOptions:
      (nonnull MLKDigitalInkRecognizerOptions *)options;

• -recognizeInk:completion:

  Performs a recognition of the input ink.

  Note that using recognize(ink:context:completion:) instead of this method may lead to better accuracy in some cases.

  Declaration

  Objective-C

  - (void)recognizeInk:(nonnull MLKInk *)ink
            completion:(nonnull MLKDigitalInkRecognizerCallback)completion;

  Parameters

  ink	Input to be recognized.
  completion	A callback for returning recognition candidates. See DigitalInkRecognizerCallback for details.

• -recognizeInk:context:completion:

  Performs a recognition of the input ink using a recognition context.

  A recognition context contains information about the size of the writing area, and the characters that have already been entered in the text area. This helps disambiguate certain cases.

  Example usage: a previous recognition has yielded the string “hello”, that has been inserted in a text field. The user then handwrites “world”. Send the present method the ink showing “world”, and “hello” as a string in context. The recognizer will most likely return the string “ world” with a leading space separating the two words.

  See DigitalInkRecognitionContext for details.

  Declaration

  Objective-C

  - (void)recognizeInk:(nonnull MLKInk *)ink
               context:(nonnull MLKDigitalInkRecognitionContext *)context
            completion:(nonnull MLKDigitalInkRecognizerCallback)completion;

  Parameters

  ink	Input to be recognized.
  context	See DigitalInkRecognitionContext for details.
  completion	A callback for returning recognition candidates. See DigitalInkRecognizerCallback for details. If nothing can be recognized, an empty list of candidates will be passed to the callback.