iOS 监听app从后台恢复到前台

1. APPDelegate中的代理方法可以监听到程序前后台切换的状态

- (void)applicationDidEnterBackground:(UIApplication * )application

{

NSLog(@"---applicationDidEnterBackground----")

// 进入后台

}

- (void)applicationDidBecomeActive:(UIApplication * )application

{

NSLog(@"---applicationDidBecomeActive----")

// 进入前台

}

- (void)applicationDidEnterBackground:(UIApplication *)application

{

NSLog(@"---applicationDidEnterBackground----")

// 进入后台

}

- (void)applicationDidBecomeActive:(UIApplication *)application

{

NSLog(@"---applicationDidBecomeActive----")

// 进入前台

}

2. 单个ViewController通过在ViewDidLoad里注册筛选器通知来监听，在dealloc中移除通知

[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(someMethod1:)

name:UIApplicationDidBecomeActiveNotificationobject:nil];