iOS监听app被杀死

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    //  - 添加通知的监听
    [self appEnterBackground];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillTerminate) name:UIApplicationWillTerminateNotification object:nil];
    NSLog(@"----%@",[[NSUserDefaults standardUserDefaults] objectForKey:@"1231"]);
}
// - 事件处理
/** 程序进入后台的通知的事件监听 */
-(void)appEnterBackground{
    [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
}
/** 程序被杀死 */
-(void)applicationWillTerminate{
    //  - 监听到 app 被杀死时候的回调....
    [[NSUserDefaults standardUserDefaults] setObject:@"1" forKey:@"1231"];
    [[NSUserDefaults standardUserDefaults] synchronize];
}