Settings page to show only once - ios

Question

I have an app which should only show the settings page once: when the app is opened for the first time.
Now this works, and when the user presses the middle button on the iPhone it then reopens the app and carries on from the main screen - that's great. But if I double click on the iPhone button and swipe the application off, it will then go to the settings screen again and not to where it was.
Why is it doing that? How can I make my app only show its settings once?
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
NSUserDefaults *settingsscreen = [NSUserDefaults standardUserDefaults];
[settingsscreen registerDefaults:[NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES],#"firstTime", nil]];
BOOL firstTime = [settingsscreen boolForKey:#"firstTime"];
if ( firstTime==YES) {
[[NSUserDefaults standardUserDefaults] setBool:YES forKey:#"SettingsShown"];
[[NSUserDefaults standardUserDefaults] synchronize];
self.window.rootViewController = [self.window.rootViewController.storyboard instantiateViewControllerWithIdentifier:#"SetUpNav"];
}
else
{
return YES;
}
}

Answer 1

Don't use if ( firstTime==YES) { based on #"firstTime", because that flag is never actually saved. You should be using the flag saved with the #"SettingsShown" key.
BOOL firstTime = [settingsscreen boolForKey:#"SettingsShown"];
if (!firstTime) {
...

Answer 2

Instead doing in appDelegate try to acheive it in setting Page itself
-(void) viewDidLoad {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
username = [defaults objectForKey:#"username"];
if (username != NULL ) {
[self selfLogin];
}
}
-(void)selfLogin{
nextPageController = [[NextPageViewController alloc]init];
[self.navigationController pushViewController:nextPageController animated:YES];
}