#pragma 獲取檔案大小
- (CGFloat) getFileSize:(NSString *)path
{
    NSFileManager *fileManager = [[NSFileManager alloc] init];
    float filesize = -1.0;
    if ([fileManager fileExistsAtPath:path]) {
        NSDictionary *fileDic = [fileManager attributesOfItemAtPath:path error:nil];//獲取檔案的屬性
        unsigned long long size = [[fileDic objectForKey:NSFileSize] longLongValue];
        filesize = 1.0*size/1024;
    }
    return filesize;
}

//獲取檔案的時間
- (CGFloat) getVideoLength:(NSURL *)URL
{
    NSDictionary *opts = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:NO]
                                                     forKey:AVURLAssetPreferPreciseDurationAndTimingKey];
    AVURLAsset *urlAsset = [AVURLAsset URLAssetWithURL:URL options:opts];
    float second = 0;
    second = urlAsset.duration.value/urlAsset.duration.timescale;
    return second;
}