Make part of UIImage transparent, or crop that region - ios

Question

I have a UIImage like so:
I want to remove a rect in the middle to leave it like so:

Answer 1

The easiest way to punch a hole through would be to add a layer mask.
#import <QuartzCore/QuartzCore.h>
Create the path you want to clip (the rect you want to punch through)
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRect:yourView.bounds];
[maskPath appendPath:[UIBezierPath bezierPathWithRect:rectToPunchThroughTheView]];
Then create a mask layer and add it to your view - CAShapeLayer will allow you to define any path
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.fillRule = kCAFillRuleEvenOdd;
maskLayer.fillColor = [UIColor blackColor].CGColor;
maskLayer.path = maskPath.CGPath;
yourView.layer.mask = maskLayer;

Answer 2

I would create a UIImage category and crop the image two times with different rects.
Here is the method I added yo my UIImage category a while ago that suited my needs good:
- (UIImage *)cropWithRect:(CGRect)rect {
// If run on a retina device scale is 2 else 1
rect = CGRectMake(rect.origin.x * self.scale,
rect.origin.y * self.scale,
rect.size.width * self.scale,
rect.size.height * self.scale);
CGImageRef imgRf = CGImageCreateWithImageInRect(self.CGImage, rect);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef
scale:self.scale
orientation:self.imageOrientation];
CGImageRelease(imageRef);
return croppedImage;
}

Answer 3

You can do this way
CGRect fullimageRect;
CGRect upperRect;
CGRect lowerRect;
UIImage *upperImage;
UIImage *lowerImage;
UIImage *finalImage;
UIGraphicsBeginImageContext(upperRect.size);
[[UIImage imageNamed:#"yourimage.png"] drawInRect:lowerRect];
upperImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIGraphicsBeginImageContext(lowerRect.size);
[[UIImage imageNamed:#"yourimage.png"] drawInRect:lowerRect];
lowerImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSLog(#"%#",upperImage);
NSLog(#"%#",lowerImage);
UIGraphicsBeginImageContext(fullimageRect.size);
[upperImage drawInRect:upperRect];
[lowerImage drawInRect:lowerRect];
finalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSLog(#"%#",finalImage);