当用户按上HOME键时

当用户按下HOME键时
#pragma mark -
#pragma mark 按下HOME键时的通知
-(void)pressHome:(NSNotification *) notification{
   NSLog(@'pressHome......');
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
 
    //注册一个通知，当用户按下HOME键时 执行pressHome:方法
     UIApplication *app = [UIApplication sharedApplication];
    [[NSNotificationCenter defaultCenter] addObserver:self
            selector:@selector(pressHome:)
            name:UIApplicationDidEnterBackgroundNotification
             object:app];
 
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

sdk3.0
UIApplicationWillTerminateNotification
sdk4.0
UIApplicationDidEnterBackgroundNotification