[IOS开发]图片压缩

不改变分辨率，将图片压缩至指定体积

+ (NSData *)compressImage:(UIImage *)image toByte:(NSUInteger)maxLength {

    // Compress by quality

    CGFloat compression = 1;

    NSData *data = UIImageJPEGRepresentation(image, compression);

    if (data.length < maxLength) return data;

    

    CGFloat max = 1;

    CGFloat min = 0;

    for (int i = 0; i < 6; ++i) {

        compression = (max + min) / 2;

        data = UIImageJPEGRepresentation(image, compression);

        if (data.length < maxLength * 0.9) {

            min = compression;

        } else if (data.length > maxLength) {

            max = compression;

        } else {

            break;

        }

    }

    return data;

}