How to merge one or more images

Merge images
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- (UIImage *)combineImage:(UIImage *)imageA imageB:(UIImage *)imageB
{
  UIGraphicsBeginImageContext(imageA.size);
 
  [imageA drawInRect:CGRectMake(0, 0, imageA.size.width, imageA.size.height)];
  [imageB drawInRect:CGRectMake(0, 0, imageB.size.width, imageB.size.height)];
 
  UIImage *combinatedImage = UIGraphicsGetImageFromCurrentImageContext();
 
  UIGraphicsEndImageContext();
 
  return combinatedImage;
}

How to resize

Resize
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#define kAppIconWidth 84
#define kAppIconHeight 66
 
// in UIImage *image your own instance
 
if (image.size.width > kAppIconWidth || image.size.height > kAppIconHeight) {
  CGSize itemSize = CGSizeMake(kAppIconWidth, kAppIconHeight);
  UIGraphicsBeginImageContext(itemSize);
  CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height);
  [image drawInRect:imageRect];
  UIImage *resizeImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
}

How to crop an image area

Crop image area
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- (UIImage *)cropImage:(UIImage *)image cropRect:(CGRect)rect
{
  CGImageRef sourceImageRef = [image CGImage];
  CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, rect);
  UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
  return newImage;
}