Accessing the *real* home folder from a sandboxed app

The preferred way to find a path for a directory within the user’s folder is to use NSSearchPathForDirectoriesInDomains (or an NSFileManager equivalent, such as URLsForDirectory:inDomains:). Problem with that is, if your app is sandboxed, these fuctions won’t give you paths the actual directories you’ve asked for, but rather the equivalent paths within your app’s container, even if you’re using entitlements which allow access to those paths.

So, let’s say you want to get the path for the user’s Documents directory. You’d end up with something like this:

- (NSURL*) getDocumentsDirectoryURL
{
    NSArray* paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES );
    NSString* documentsPath = paths[0];
    return [NSURL fileURLWithPath:documentsPath];
}

You might expect to get back something like file://localhost/Volumes/SSD/Users/zach/Documents/ (at least, you’d expect that if your name was Zach). But you might be surprised when you actually get something more like file://localhost/Volumes/SSD/Users/zach/Library/Containers/com.mycompany.myapp/Data/Documents/.

If you really want the path to the real Documents directory (in ~/Users/zach/Documents), you need to do something like this:

- (NSURL*) getDocumentsDirectoryURL
{
    struct passwd *pw = getpwuid(getuid());
    NSString* realHomeDir = [NSString stringWithUTF8String:pw->pw_dir];
    NSString* documentsPath = [realHomeDir stringByAppendingPathComponent:@"Documents"];
    return [NSURL fileURLWithPath:documentsPath];
}

Admittedly, there aren’t many cases where you would want to do this. One reason you’d do this is to set the default location for an open/save file dialog – navigating the user to the Documents directory in your app container would be quite confusing. In my case, VideoBuffet really wants to find all the movies in your Movies folder, and there of course aren’t any in the Movies folder equivalent of the app container.

Notably, if you’re doing something like getting the path to Caches or Library (say, to save some settings into a .plist), you definitely want to use the normal NSSearchPathForDirectoriesInDomains method, because those should be saved into the app conainer.

Update 05/11/17:This is still a valid thing to do today, and here’s how you’d do it in Swift 3:


func getDocumentsDirectoryURL() -> URL {
	let pw = getpwuid(getuid());
	let home = pw?.pointee.pw_dir
	let homePath = FileManager.default.string(withFileSystemRepresentation: home!, length: Int(strlen(home)))
	let documentsPath = (homePath as NSString).appendingPathComponent("Documents")
	return URL(fileURLWithPath: documentsPath)
}