///绘图显示
-(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
}

 

参考：

https://blog.csdn.net/u012198553/article/details/43051005

https://www.cnblogs.com/xm5mao/p/3964701.html