iOS 捕捉home事件

1. AppDelegate

2. NSNotificationCenter

- (void)viewDidLoad
{
    [super viewDidLoad];
    // 注册
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(hahaha) name:UIApplicationDidBecomeActiveNotification object:nil];
}
//
- (void)hahaha
{
    // 
}