Edit AllPages

I’ve been trying to find a way to access either a directory, or a text file with a list of file paths and be able to order them in to a hierarchical list in an NSDictionary.

For instance, if I open a folder that contains one file, my dictionary would look something like this:

“Path” = “/Path/To/Root/Folder”, “Is Directory” = YES, “Contents” = { “Path” = “/Path/To/Root/Folder/File”, “Is Directory” = NO }

I haven’t even begun to tackle the ordering of a text file of paths, but I did get a start on traversing through a folder. I ran into a problem, though…

My code (shown below) runs fine for a folder that contains no more than around 240 subfiles/subfolders, but once it gets close to 240, it errors out and says that NSMutableDictionary object:forKey: cannot insert nil object. I’m thinking that the problem might be that my method calls itself for each new file/folder it finds and maybe I can only do that so many times? I’m guessing I’m going about it in sort of a loopy way, but I couldn’t think of another way to do it. I tried using NSFileManager’s subpathsAtPath: method as well, but I still had to work my way through the list and so when I got to around 240 it errored out again.

Any help would be appreciated.


The term you are looking for is “Recursion”. It means that a function or method directly or indirectly calls itself. Indeeed, if recursion becomes too deep, the system stack is corrupted and the usual result is a segmantation fault. The error you describe is probably not due to recursion.

Why didn’t you just use - (NSDirectoryEnumerator *)enumeratorAtPath:(NSString *)path “Because the enumeration is deep�that is, it lists the contents of all subdirectories�this enumerator object is useful for performing actions that involve large file-system subtrees. “

Apple even provides a sample right in the documentation:

NSString *file; NSString *docsDir = [NSHomeDirectory() stringByAppendingPathComponent: @”Documents”]; NSDirectoryEnumerator *dirEnum = [[NSFileManager defaultManager] enumeratorAtPath:docsDir];

while (nil != (file = [dirEnum nextObject])) { if (file pathExtension] isEqualToString: @”doc”]) { [self scanDocument: [docsDir stringByAppendingPathComponent:file; } }

That is what I tried doing in the first place, and it lists all the files correctly, but I’m not sure how to break up the paths and organize them in a similar fashion as my above code. Using NSFileManager’s enumeratorAtPath (or even the subpathsAtPath) method gives all the right information, but I’m not sure how to tackle the next step.

See also:

Thanks for all the help, I’ll take some time and see what I can crank out.