代码片段

Combine two UIImages

To add two UIImages together you need to make use of Graphics Context.

- (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2 {  
    UIGraphicsBeginImageContext(image1.size);  
  
    // Draw image1  
    [image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];  
  
    // Draw image2  
    [image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];  
  
    UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();  
  
    UIGraphicsEndImageContext();  
  
    return resultingImage;  
}

 

  

Create a UIImage from a part of another UIImage

This requires a round-trip to Core Graphics land:

- (UIImage *)imageFromImage:(UIImage *)image inRect:(CGRect)rect {  
    CGImageRef sourceImageRef = [image CGImage];  
    CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, rect);  
    UIImage *newImage = [UIImage imageWithCGImage:newImageRef];  
    CGImageRelease(newImageRef);  
    return newImage;  
} 

 

 

http://blog.csdn.net/arthurchenjs/article/details/6696628