Use NSOpenpanel and NSfilemanager to find contents of directory - objective-c

Question

I'm new to objective-c so please excuse my lack of knowledge. I have a snippet of code here that I can't seem to get working properly. What I'd like to do is present a directory selection panel upon a button click. Once the user selects a directory I'd like to make an array of everything in the directory. Eventually I want to use this array to have a list of sub-directories and files (everything in the directory the user selects) to be copied to another location.
I have a warning that says Instance method '-contentsofdirectoryaturl:options:error' not found (return type defaults to id). I'm not exactly sure what that means or how to fix it and I suspect that this is my problem. Any advice provided would be great. Thanks!
- (IBAction)selectfiles:(id)sender {
NSOpenPanel *openPanel = [NSOpenPanel openPanel];
[openPanel setCanChooseDirectories:YES];
[openPanel setCanChooseFiles:NO];
[openPanel setAllowsMultipleSelection:NO];
if ( [openPanel runModal] == NSOKButton ) {
NSArray *accountPath = [openPanel URLs];
NSLog (#"%#", accountPath);
NSFileManager *filemgr;
filemgr = [NSFileManager defaultManager];
NSArray *contents;
contents = [filemgr contentsOfDirectoryAtURL:accountPath options:(NSDirectoryEnumerationSkipsHiddenFiles) error:nil];
}
}

Answer 1

contentsOfDirectoryAtURL: has an additional argument includingPropertiesForKeys: which you have omitted. That is why the compiler warns you. That argument is a list of properties you want to be prefetched. In the simplest case, you can specify an empty array.
Another error is that [openPanel URLs] returns an array of URLs, even if only one item is selected.
So your code should look like this:
NSURL *accountPath = [[openPanel URLs] objectAtIndex:0];
NSLog (#"%#", accountPath);
NSFileManager *filemgr;
filemgr = [NSFileManager defaultManager];
NSArray *contents;
contents = [filemgr contentsOfDirectoryAtURL:accountPath
includingPropertiesForKeys:[NSArray array]
options:(NSDirectoryEnumerationSkipsHiddenFiles)
error:nil];