iOS 壓縮圖檔大小

對于這個圖檔壓縮真的沒法說 單壓縮比 沒法達到自己想要的結果，隻能組合 代碼為建立的UIImage 的分類

- (UIImage *)scaleFromImage:(UIImage *)image
{
    if (!image)
    {
        return nil;
    }
    NSData *data =UIImagePNGRepresentation(image);
    CGFloat dataSize = data.length/1024;
    CGFloat width  = image.size.width;
    CGFloat height = image.size.height;
    CGSize size;
    
    if (dataSize<=50)//小于50k
    {
        return image;
    }
    else if (dataSize<=100)//小于100k
    {
        size = CGSizeMake(width/1.f, height/1.f);
    }
    else if (dataSize<=200)//小于200k
    {
        size = CGSizeMake(width/2.f, height/2.f);
    }
    else if (dataSize<=500)//小于500k
    {
        size = CGSizeMake(width/2.f, height/2.f);
    }
    else if (dataSize<=1000)//小于1M
    {
        size = CGSizeMake(width/2.f, height/2.f);
    }
    else if (dataSize<=2000)//小于2M
    {
        size = CGSizeMake(width/2.f, height/2.f);
    }
    else//大于2M
    {
        size = CGSizeMake(width/2.f, height/2.f);
    }
    NSLog(@"%f,%f",size.width,size.height);
    UIGraphicsBeginImageContext(size);
    [image drawInRect:CGRectMake(0,0, size.width, size.height)];
    UIImage *newImage =UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    if (!newImage)
    {
        return image;
    }
    return newImage;
}