Where can a sandboxed Mac app save files?

That code snippet works on the Mac regardless of whether your application is sandboxed.

In a non-sandboxed Mac app, path will refer to the Documents folder in your home: e.g. /Users/username/Documents.

In a sandboxed app, it refers to a folder within the app sandbox: e.g. /Users/username/Library/Containers/com.yourcompany.YourApp/Documents

See the docs for details.

Apple's Sandboxing guide is very useful, found here.

You basically have a folder dedicated for your app, as described by theAmateurProgrammer in reply to my question here.

~/Library/Container/com.yourcompany.yourappname/

Here is what I have so far, I will improve it later:

//Create App directory if not exists:
NSFileManager* fileManager = [[NSFileManager alloc] init];
NSString* bundleID = [[NSBundle mainBundle] bundleIdentifier];
NSArray* urlPaths = [fileManager URLsForDirectory:NSApplicationSupportDirectory 
                                        inDomains:NSUserDomainMask];

NSURL* appDirectory = [[urlPaths objectAtIndex:0] URLByAppendingPathComponent:bundleID isDirectory:YES];

//TODO: handle the error
if (![fileManager fileExistsAtPath:[appDirectory path]]) {
    [fileManager createDirectoryAtURL:appDirectory withIntermediateDirectories:NO attributes:nil error:nil];
}