UIImage 合成

代码片段：

    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();