iOS开发 图片压缩失真问题解决

iOS开发过程中，经常会用到图片压缩，总结一下

1.这种方法会使图片失真

-  (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();
    return scaledImage;
}

2.此方法图片不会失真

- (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();
    return scaledImage; 
}