iOS改变图片尺寸

- (UIImage *)originImage:(UIImage *)image scaleToSize:(CGSize)size
{
    UIGraphicsBeginImageContext(size);  //size 为CGSize类型，即你所需要的图片尺寸

    [image drawInRect:CGRectMake(0, 0, size.width, size.height)];  

    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();  

    UIGraphicsEndImageContext();  

    return scaledImage;   //返回的就是已经改变的图片
}