Adding a UIGestureRecognizer taking priority over all other interactions - ios

When I tap on a UIButton, a UIView MyView appear from the bottom a cover a third of the screen. I would like that when I tap somewhere outside this view, it disappears.
I thought about adding another transparent UIView right under MyView and add a tab gesture on it with the dismiss function but I'm sure there is something cleaner than this.
So I thought about adding the tap gesture MyTapGesture to dismiss MyView on self.view of the UIViewController. The problem is that outside this view, I have other UIControls and gestures that capture also any touch at the same time than MyTapGesture.
How can I make MyTapGesture the priority gesture outside MyView and ignore all other gesture, taps, etc...?

You may have to use the gesture delegate methods to handle two tapGestureRecognizer activate the one you need depending on scenario
#pragma mark - UIGestureRecognizerDelegate methods
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
return YES;
}
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
if ([tapGestureRecognizer1 isEqual:gestureRecognizer]) {
return [tapGestureRecognizer2 isEqual:otherGestureRecognizer];
}
if ([tapGestureRecognizer2 isEqual:gestureRecognizer]) {
return [tapGestureRecognizer1 isEqual:otherGestureRecognizer];
}
return NO;
}

Related

UIGestureRecognizer under the other UIView

I couldn't find a solution for my small problem with Gestures and hierarchy. There you have how it is looks like:
-superview
--view A
---objectViewA z UIGestureRecognizer
--view B
---objectViewB z UIGestureRecognizer
On the beginning viewA and viewB are hidden. User unhide it as he wants. When the viewB is not covering viewA I can move objectViewA but if we will unhide viewB I can move objectViewB but objectViewA doesn't return any touch.
I added shouldRecognizeSimultaneouslyWith delegate but it doesn't work. It didn't get any action.
How to fix this problem? I will be glad!
You can use the UIGestureRecognizerDelegate to determine if viewB should handle the gesture or pass it down the hierarchy to viewA.
https://developer.apple.com/reference/uikit/uigesturerecognizerdelegate
You have to use the delegate method like this.
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{
if ([touch.view isDescendantOfView:(Your View)]) {
return YES;
}
return NO;
}
I hope it will help you.

Are subviews automatically added as listeners to their superview's UIGestureRecognizers?

I have a swipe gesture attached to a UIView that doesn't seem to be registering when the swipe is on top of it's subviews.
One of solution is to check is gesture point inside your subview or not,
there is a useful C function:
/* Return true if `point' is contained in `rect', false otherwise. */
bool CGRectContainsPoint(CGRect rect, CGPoint point)
that you can use like this:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
return CGRectContainsPoint(subview.frame, [touch locationInView:self.view]);;
}
The other solutions should work, but a potentially easier one is to set subview.userInteractionEnabled = false in the subview if it doesn't have its own event handlers.
Let's say A is the root UIView which you want to receive swipes, and B is a subview of A that you don't really want to receive swipes.
if you do not want to receive any gestures on B, you can userInteractionEnabled = false on it
if you still want to receive some gestures on B (but not a swipe)
you must subclass B so that you can implement this method, and implement this method in B
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
if ([gestureRecognizer isKindOfClass:UISwipeGestureRecognizer]) {
return NO;
}
return YES;
}
You can also see how you may get a wide range of functionality from implementing gestureRecognizer:shouldReceiveTouch:

Enabling touch event on Objects In a UIScrollview

I've a scrollview that has a UIView on it and on those Views, there's a UIImageView on it, three UILabel on it, I want to enable user Interaction on it, but wouldn't work. I've enabled setUserInteraction for both the UIView, UIScrollView, UILabels, UIImageView none is Responding to click actions at all. The layout look like the Image Below....
implement
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
so the gestures of the uiscroll view won't conflict with the subview's recognisers
basically what happens is that the UIScrollView won't pass the events to its subviews because the default of the above method is to return NO
This sounds too easy to be the problem, but I've made the following mistake: Everything is set just right, but I did not drag out one of the SentEvents like TouchUpInside to an action in the implementation.
check this way,
1> first check whether your view controller respond to UIGestureRecognizerDelegate this way
#interface RootViewController : UIViewController<UIGestureRecognizerDelegate>
2> then in design check you map scrollview property and delegate properly
3> apply this code in viewDidload
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapditected)];
tapGesture.delegate = self;
// prevents the scroll view from swallowing up the touch event of child buttons
tapGesture.cancelsTouchesInView = NO;
[self.scroller addGestureRecognizer:tapGesture];
4> check you apply this code
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}
5> if all goes wll then this method should detected
-(void)tapditected{
}

iOS gesture collisions between slider and pan gesture on controller

I am using ECSlidingViewController for hamburger menu and I added code to my viewDidLoad method:
[self.slidingViewController.topViewController.view addGestureRecognizer:self.slidingViewController.panGesture];
Now I have pan gesture to show right menu or to hide. It's okay. But I have on view slider and it's really hard to get him working. I must tap on exact position. Is it possible to set that in exact rectangle (in view that contains slider) the slider would be answering on gesture and on other parts it would be working as now?
And one more question. When I have navigation controller with table and then I went on detail and then I show right menu it's okay but when I want to close it by pan I first go back in navigation and then close menu. Is it possible to change this order?
Have you tried setting UIGestureRecognizerDelegate and handling the both gesture recognizes in similar fashion as described in FAO?
e.g.:
#pragma mark - UIGestureRecognizerDelegate
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
if ([otherGestureRecognizer.view isKindOfClass:[UISlider class]]) {
return YES;
} else {
return NO;
}
}

Tap on UIBarButtonItem is not ignored by TapGestureRecognizer

I have a view with a UIToolbar with a few UIBarButtonItems and a UITableView containing some UITextFields.
I would like to dismiss the keyboard for a textfield with a tap anywhere. Therefore I added a TapGestureRecognizer to the view. To avoid that the TapgestureRecognizer handles taps on the UIBarButtonItems I added the following method (delegate is set).
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
UIView *view = touch.view;
while (view) {
NSLog(#"Class of view: %#", NSStringFromClass([view class]));
view = view.superview;
}
// Disallow recognition of tap gestures in the toolbar
if ([touch.view isKindOfClass:[UIToolbar class]]) {
return NO;
}
if ([touch.view.superview isMemberOfClass:[UIToolbar class]]) {
return NO;
}
return YES;
}
A UIBarButtonItem is not a view itself, but it has UIToolbar as its superview. When I use the above method, the check for isKindOfClass:[UIToolbar class] does not seem to work for all taps on the toolbar. However the check for the superview with isMemberOfClass:[UIToolbar class] works.
I don't understand this. Maybe someone can explain this behavior?
You shouldn't rely on the view hierarchy around private view classes. It could change at any time.
A better approach is to add the gesture to the table view (or other appropriate view which represents the area you're interested in). Just be sure to enable and disable the gesture at appropriate times so as not to block the usual table operation.

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