在单独的类中创建的带有UIView的UISwipeGestureRecognizer无法正常工作

Question

I created a UIView in a separate class, and I am trying to animate it in my ViewController. It is supposed to work like the notification screen on the iPhone that appears when you swipe down, and then you can swipe it back up.

I can get my custom view to swipe down, but when I try to swipe it back up, the swipe up gesture is not being initiated.

I am a novice, so any help is greatly appreciated!

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    NotificationView *notificationView = [[NotificationView alloc]init];
    [self.view addSubview:notificationView];



    UISwipeGestureRecognizer *swipeDownGestureRecognizer = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeDown:)];
    swipeDownGestureRecognizer.direction = UISwipeGestureRecognizerDirectionDown;

    UISwipeGestureRecognizer *swipeUpGestureRecognizer = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeUp:)];
    swipeUpGestureRecognizer.direction = UISwipeGestureRecognizerDirectionUp;

    [self.view addGestureRecognizer:swipeDownGestureRecognizer];
    [notificationView addGestureRecognizer:swipeUpGestureRecognizer];

}

-(void) swipeUp: (UISwipeGestureRecognizer *) recognizer{

    UIView *notificationView = [[NotificationView alloc]init];
    notificationView = recognizer.view;

    [UIView animateWithDuration:2.0 animations:^{
        notificationView.frame = CGRectMake(0, 0, 414, 723);
    }];

}

-(void) swipeDown: (UISwipeGestureRecognizer *) recognizer{

    UIView *notificationView = [[NotificationView alloc]init];
    notificationView = recognizer.view;

    [UIView animateWithDuration:2.0 animations:^{
        notificationView.frame = CGRectMake(0, 723, 414, 723);
    }];

}

Answer 1

You should create a property with your notificationView and keep a reference to it, and not create a new one over and over.

@property (strong, nonatomic) NotificationView *notificationView;

And in your viewDidLoad :

       _notificationView = [[NotificationView alloc] init];

// Important line to solve your problems on gestures not fired off on your notification view
_notificationView.userInteractionEnabled = YES;

        [self.view addSubview:_notificationView];

and simply change:

-(void)swipeDown:(UISwipeGestureRecognizer *)recognizer {

    [UIView animateWithDuration:2.0 animations:^{
        _notificationView.frame = CGRectMake(0, 723, 414, 723);
    }];

}

You should look into a tutorial on how properties work. And you should look into This Thread to avoid animations getting called multiple times etc by handling gesture states.

Answer 2

应该将ViewDidLoad中的notificationView分配给viewControllers属性，并且不应在手势识别器操作中分配初始化视图。