Objective c 如何在iOS中获取文档目录中的各种文件夹内容？

我可以在

表视图中列出
文档目录
中的内容。但我有50个文件夹，我已经从文件目录的不同来源下载。现在我要获取所有50个文件夹的内容以及文档目录内容

//This is my Code...
NSArray * paths = NSSearchPathForDirectoriesInDomains ( NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSError * error;
NSArray *extensions = [NSArray arrayWithObjects:@"mp4", @"folder", @"mov", @"m4v", @"pdf", @"doc", @"xls", @"mp3" ,nil];
directoryContents =  [[NSFileManager defaultManager]
                      contentsOfDirectoryAtPath:documentsDirectory error:&error];
directoryContents = [directoryContents filteredArrayUsingPredicate: 
                      [NSPredicate predicateWithFormat:@"pathExtension IN %@", extensions ]];
NSLog(@"directoryContents ====== %@",directoryContents);

//这将只列出文件夹或子文件夹中的所有内容，而不列出文件夹。只需在if条件下将匹配的字符串传递给扩展名

test=[[NSMutableArray alloc]init];// allocate mutable array Globally
 NSArray * paths = NSSearchPathForDirectoriesInDomains ( NSDocumentDirectory, NSUserDomainMask, YES);
 NSString *documentsDirectory = [paths objectAtIndex:0];

NSDirectoryEnumerator *de = [[NSFileManager defaultManager] enumeratorAtPath:documentsDirectory] ;

NSString *file;
while ((file = [de nextObject]))

 if (([[file pathExtension] isEqualToString:@"mp3"])  ||  ([[file pathExtension]        isEqualToString:@"mp4"]) ||  ([[file pathExtension] isEqualToString:@"mov"]) || ([[file pathExtension] isEqualToString:@"avi"]) || ([[file pathExtension] isEqualToString:@"mkv"]))

    [test addObject:file.lastPathComponent];
    NSLog(@"%@",test);