计算视屏资源的大小

/**
 * @method
 *
 * @brief 根据路径获取视频时长和大小
 * @param path       视频路径
 * @return    字典    @"size"－－文件大小   @"duration"－－视频时长
 */
- (NSDictionary *)getVideoInfoWithSourcePath:(NSString *)path;

- (NSDictionary *)getVideoInfoWithSourcePath:(NSString *)path{
    AVURLAsset * asset = [AVURLAsset assetWithURL:[NSURL fileURLWithPath:path]];
    CMTime   time = [asset duration];
    int seconds = ceil(time.value/time.timescale);

    NSInteger   fileSize = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil].fileSize;

    return @{@"size" : @(fileSize),
             @"duration" : @(seconds)};
}