How to determine app is in active state or inactive state ios?

Question

I need to know when an App is in Foreground, it is in active state or inactive state ?

If my App is in inactive state I need to fire the Logout Protocol and destroy the current user's session,

- (void)applicationWillResignActive:(UIApplication *)application
{
    NSLog(@"App is not active logout success");
}

Is there any appDelegate method which tell me that app is in inactive state, any code example will help me a lot.

If need work with "NSNotificationCenter", in which class can I add the code and who will be observer.

Answer 1

To test for the state you can do something like:

[[UIApplication sharedApplication] applicationState]==UIApplicationStateInactive

or

[[UIApplication sharedApplication] applicationState]==UIApplicationStateActive

If you want to be notified you can do:

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(yourselector:)
                                                 name:UIApplicationDidBecomeActiveNotification object:nil];

or

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(yourselector:)
                                                 name:UIApplicationDidEnterBackgroundNotification object:nil];

You can do other notifications too (from https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIApplication_Class/):

UIApplicationDidBecomeActiveNotification UIApplicationDidChangeStatusBarFrameNotification UIApplicationDidChangeStatusBarOrientationNotification UIApplicationDidEnterBackgroundNotification UIApplicationDidFinishLaunchingNotification UIApplicationDidReceiveMemoryWarningNotification UIApplicationProtectedDataDidBecomeAvailable UIApplicationProtectedDataWillBecomeUnavailable UIApplicationSignificantTimeChangeNotification UIApplicationUserDidTakeScreenshotNotification UIApplicationWillChangeStatusBarOrientationNotification UIApplicationWillChangeStatusBarFrameNotification UIApplicationWillEnterForegroundNotification UIApplicationWillResignActiveNotification UIApplicationWillTerminateNotification UIContentSizeCategoryDidChangeNotification

If you want to use the app delegate, you can use:

- (void)applicationDidEnterBackground:(UIApplication *)application {}

or

- (void)applicationDidBecomeActive:(UIApplication *)application {}