iOS 两张图片合成

- (UIImage *)composeImage:(UIImage*)firstImage secondImage:(UIImage*)secondImage
{
UIGraphicsBeginImageContext(firstImage.size);

[firstImage drawInRect:CGRectMake(0, 0, firstImage.size.width, firstImage.size.height)];
   
//    CGFloat height = mkvc.headerView.frame.size.height * 2 * 0.84;
//    CGFloat width = mkvc.headerView.frame.size.width * 2 * 0.84;
//    CGFloat y = mkvc.headerView.frame.origin.y * 2 * 0.84;
//    CGFloat x = mkvc.headerView.frame.origin.x * 2 * 0.84;
//   
// [secondImage drawInRect:CGRectMake(x, y, width, height)];
    [secondImage drawInRect:CGRectMake(0, 0, 540, 540)];

UIImage *resImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resImage;
}