利用Notification判斷裝置是否進入背景執行

- (void)viewDidLoad

{

    [super viewDidLoad];

    

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

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

}

-(void)appDidEnterBackground:(NSNotification *)_notification

{

    isAppInBackground = YES;

    NSLog(@"App is in background");

}

-(void)appDidBecomeActiveBackground:(NSNotification *)_notification

{

    isAppInBackground = NO;

    NSLog(@"App is in foreground");

    [[UIApplication sharedApplication] cancelAllLocalNotifications];

}