//图片会失真

- (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();returnscaledImage;}

//此方法图片不失真
- (UIImage*)originImage:(UIImage *)image scaleToSize:(CGSize)size

    {

        // 第一个参数表示区域大小。第二个参数表示是否是非透明的。如果需要显示半透明效果,需要传NO,否则传YES。第三个参数就是屏幕密度了

        UIGraphicsBeginImageContextWithOptions(size,NO, [UIScreen mainScreen].scale);

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

        UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();

        UIGraphicsEndImageContext();

        returnscaledImage;

    }