A UIImage category which provides “visible” pixel cropping capabilities.

A given image can be rectangularly cropped based on calculated insets to “visible” pixels. Visible pixels are those whose alpha component are greater than or equal to a given alpha threshold.

Available on github: https://github.com/levigroker/GRKImageCrop



If you’re using CocoPods it’s as simple as adding this to your Podfile:

pod 'GRKImageCrop'

otherwise, simply add the contents of the GRKImageCrop subdirectory to your project.


To use, simply import UIImage+GRKImageCrop.h:

#import "UIImage+GRKImageCrop.h"

Then you can use the category to create a cropped image from a given image:

[image cropImageBelowAlphaThreshold:0.0f completion:^(UIImage *croppedImage, NSError *error) {
    if (croppedImage)
        //Use croppedImage
        //Hanlde error

The only expected error would be memory related.

Additional documentation is available in UIImage+GRKImageCrop.h and example usage can be found in the GRKImageCropTestApp.

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