- (unsigned long long)enumeratorWithPath:(NSString *)filePath{
   //注釋 ios的文件大小以1000為單位,不是以1024作為單位.
   unsigned long long folderSize = 0 ;
   NSFileManager * fileManager = [NSFileManager defaultManager];
   //文件是否存在
   BOOL isExist;
   //是否文件夾
   BOOL isFolder;
   isExist  = [fileManager fileExistsAtPath:filePath isDirectory:&isFolder ];
   if (!isExist) {
      return 0;
   }
   if (isFolder) {
      //是文件夾
      NSEnumerator * childFileEnumerator = [[fileManager subpathsAtPath:filePath] objectEnumerator];
      NSString * fileName;
      while ((fileName = [childFileEnumerator nextObject]) != nil) {
         NSString * fileAbsolutePath = [filePath stringByAppendingPathComponent:fileName];
         folderSize += [[fileManager attributesOfItemAtPath:fileAbsolutePath error:nil] fileSize];
         NSLog(@"%@",fileAbsolutePath);
      }
   }else{
      //不是文件夾
      folderSize = [[fileManager attributesOfItemAtPath:filePath error:nil] fileSize];
   }
   NSLog(@"%.2llu",folderSize);
   return folderSize;
}