iOS 监听 Home键和从新进入程序

//监听是否触发home键挂起程序.

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillResignActive)                                               name:UIApplicationWillResignActiveNotification object:nil];

//监听是否从新进入程序程序.

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