- (NSString *)applicationDocumentsDirectory {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                         NSUserDomainMask,
                                                         YES);
    NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
    return basePath;
}

// elsewhere, like in -application:didFinishLaunching:withOptions:
NSLog(@"app doc directory: %@", [self applicationDocumentsDirectory]);