Using applicationDidBecomeActive To Check If User Logged In - ios

Question

I have an app that has a "Home Screen" with login and register options. When a user completes one of the above the data is stored in a shared instance. Now for security reasons I was looking at using the applicationDidBecomeActive to periodically check to make sure the user is still active on the server or not blocked by calling a method in the shared instance. If the user is not active the app kicks them to the home screen with a prompt.
My issue is however that when the app loads for the first time `applicationDidBecomeActive is called and because the user is not logged in you end up with a loop.
What is the correct approach for dealing with this issue? Ideally I want to use applicationDidBecomeActive but I only want to perform the check whilst in the account section of the app.
Any help would be great.
Thanks.

Answer 1

There are several ways of implementing this.
Way 1: Fire a Notification using NotificationCenter.default and implement a listener in your Accounts-ViewController.
Way 2: In your AppDelegate, get active ViewController (depends on which rootViewController you are using) and if that ViewController has the type AccountVC trigger a public function.
Way 3: Combine or use Way1 and Way2 in a different object and notify your ViewController in your preferred way.
And many more.
Post some code for more specific help :)

Answer 2

You can use either of the following methods to deal with the issue.
Approach 1
- (void)checkWhetherAppIsActive {
UIApplicationState appState = [[UIApplication sharedApplication] applicationState];
if (appState == UIApplicationStateActive) {
}else if (appState == UIApplicationStateInactive) {
}else if (appState == UIApplicationStateBackground) {
}
}
Approach 2
[[NSNotificationCenter defaultCenter] addObserverForName:UIApplicationWillResignActiveNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * _Nonnull note) {
}];
[[NSNotificationCenter defaultCenter] addObserverForName:UIApplicationWillEnterForegroundNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * _Nonnull note) {
}];
[[NSNotificationCenter defaultCenter] addObserverForName:UIApplicationWillTerminateNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * _Nonnull note) {
}];

Answer 3

When the user logs in , generate an expiryTimeStamp. And whenever the app is active, you can check the currentTimestamp to expiryTimeStamp . If the currentTimestamp is before the expiryTimeStamp, then consider it as active session!
- (void)applicationDidBecomeActive:(UIApplication *)application {
//compare current NSDate with expiryDate
if(current date is before expiry date){
//active session
}else{
//log out the user
}
}
You can generate expiry date as:
-(void)generateExpiryTimeStamp{
[[NSUserDefaults standardUserDefaults]setObject:[NSDate dateWithTimeIntervalSinceNow:900] forKey:#"tokenExpiry"]; //Expiry date Set to 15mins
[[NSUserDefaults standardUserDefaults]synchronize];
}