UIGestureRecognizer blocks subview for handling to

Question

I'm trying to figure out how this is done the right way. I've tried to depict the situation:

I'm adding a UITableView as a subview of a UIView. The UIView responds to a tap- and pinchGestureRecognizer, but when doing so, the tableview stops reacting to those two gestures (it still reacts to swipes).

I've made it work with the following code, but it's obviously not a nice solution and I'm sure there is a better way. This is put in the UIView (the superview):

-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
    if([super hitTest:point withEvent:event] == self) {
        for (id gesture in self.gestureRecognizers) {
            [gesture setEnabled:YES];
        }
        return self;
    }
    for (id gesture in self.gestureRecognizers) {
        [gesture setEnabled:NO];
    }
    return [self.subviews lastObject];
}

Answer 1

I was displaying a dropdown subview that had its own tableview. As a result, the touch.view would sometimes return classes like UITableViewCell. I had to step through the superclass(es) to ensure it was the subclass I thought it was:

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
    UIView *view = touch.view;
    while (view.class != UIView.class) {
        // Check if superclass is of type dropdown
        if (view.class == dropDown.class) { // dropDown is an ivar; replace with your own
            NSLog(@"Is of type dropdown; returning NO");
            return NO;
        } else {
            view = view.superview;
        }
    }

    return YES;
}

Answer 2

I had a very similar problem and found my solution in this SO question. In summary, set yourself as the delegate for your UIGestureRecognizer and then check the targeted view before allowing your recognizer to process the touch. The relevant delegate method is:

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
       shouldReceiveTouch:(UITouch *)touch

Answer 3

It is possible to do without inherit any class.

you can check gestureRecognizers in gesture's callback selector

if view.gestureRecognizers not contains your gestureRecognizer,just ignore it

for example

- (void)viewDidLoad
{
    UITapGestureRecognizer *singleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self     action:@selector(handleSingleTap:)];
    singleTapGesture.numberOfTapsRequired = 1;
}

check view.gestureRecognizers here

- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer
{
    UIEvent *event = [[UIEvent alloc] init];
    CGPoint location = [gestureRecognizer locationInView:self.view];

    //check actually view you hit via hitTest
    UIView *view = [self.view hitTest:location withEvent:event];

    if ([view.gestureRecognizers containsObject:gestureRecognizer]) {
        //your UIView
        //do something
    }
    else {
        //your UITableView or some thing else...
        //ignore
    }
}

Answer 4

Building on @Pin Shih Wang answer. We ignore all taps other than those on the view containing the tap gesture recognizer. All taps are forwarded to the view hierarchy as normal as we've set tapGestureRecognizer.cancelsTouchesInView = false. Here is the code in Swift3/4:

func ensureBackgroundTapDismissesKeyboard() {
    let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(handleTap))
    tapGestureRecognizer.cancelsTouchesInView = false
    self.view.addGestureRecognizer(tapGestureRecognizer)
}

@objc func handleTap(recognizer: UIGestureRecognizer) {
    let location = recognizer.location(in: self.view)
    let hitTestView = self.view.hitTest(location, with: UIEvent())
    if hitTestView?.gestureRecognizers?.contains(recognizer) == .some(true) {
        // I dismiss the keyboard on a tap on the scroll view
        // REPLACE with own logic
        self.view.endEditing(true)
    }
}

Answer 5

One possibility is to subclass your gesture recognizer (if you haven't already) and override -touchesBegan:withEvent: such that it determines whether each touch began in an excluded subview and calls -ignoreTouch:forEvent: for that touch if it did.

Obviously, you'll also need to add a property to keep track of the excluded subview, or perhaps better, an array of excluded subviews.

Answer 6

I was also doing a popover and this is how I did it

func didTap(sender: UITapGestureRecognizer) {

    let tapLocation = sender.locationInView(tableView)

    if let _ = tableView.indexPathForRowAtPoint(tapLocation) {
        sender.cancelsTouchesInView = false
    }
    else {
        delegate?.menuDimissed()
    }
}