iOS 切割图片

 - (UIImage *)CutImageWithImage:(UIImage *)image withRect:(CGRect)rect
 {
     //使用CGImageCreateWithImageInRect方法切割图片，第一个参数为CGImage类型，第二个参数为要切割的CGRect
     CGImageRef cutImage = CGImageCreateWithImageInRect(image.CGImage, rect);
     //将切割出得图片转换为UIImage
     UIImage *resultImage = [UIImage imageWithCGImage:cutImage];
     return resultImage;
 }