2. NSNotificationCenter to get native events alert

This helps to get know about NSNotificationCenter.

We can register the events notifications via NSNotificationCenter, when the event trigger then notification center will send the notification for corresponding events.

Register using the following lines of code:

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

//name is a NSString you can give available events in xcode 

Then when the app did entered background it will call the below customFunction funtion

-(void) customFunction

{

// custom code

NSLog(@"Application enter into background");

}