通知实现ios前后台切换管理

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleBackground) name:UIApplicationDidEnterBackgroundNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleResignActive) name:UIApplicationWillResignActiveNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleBecomeActive) name:UIApplicationDidBecomeActiveNotification object:nil];