I have a super view that has a UITapGestureRecognizer on it. It allows touches within the view because there are clickable items within the view.
When these items are clicked on, I want to take a specific action, not the generic one that covers the entire superview. Unfortunately in my TouchDown event of my child control I don't know how to stop the event here. I know I could create a kludge flag, but this seems like the wrong way to go.
Any advice?
James
OK I got a solution. Totally my problem. I was playing around with trying to get all touches to work and at one point I had set cancelTouchesInView = true on the UITapGestureRecognizer superview. While this didn't stop the other touches from happening, for whatever reason the touches carried through to the superview as well. I understand that this explanation probably makes no sense, but that's what did it. Still trying to wrap my head around how iOS does touch.
Related
Edit: I am editing my initial question (see below for history) as I am getting new information.
I figured out that when the swipe motion starts from inside the button bounds, we never receive TouchesEnded or TouchesCancelled, only TouchesMoved. However, if I can react on WillEnddragging, it would be great. Is it possible to cancel a gesture on WillEndDragging and also pass this cancel down the children chain?
History:
I am using Xamarin Forms and I have the following issue
I have custom controls part of native scrolling views, like ScrollView or CollectionView, that remain in "clicked" state after the finger enters them but then initiates a scroll gesture.
I had a similar issue on UWP in the past and managed to solve it with the UIElement.PointerCaptureLost event.
Sorry if I am wasting your time on trivial stuff, but I am really stuck and I greatly appreciate your help.
I have tried different approaches suggested, including setting DelaysContentTouches to NO, and playing around with CanCancelContentTouches and overriding TouchesShouldCancelInContentView to always return NO, in a ScrollView custom renderer.
I have had a read of
Allow UIScrollView and its subviews to both respond to a touch
and
UIScrollView sending touches to subviews
Maybe the accepted answer here helps, but I am not sure how to get the tag of my custom view.
What I am expecting is my custom controls to receive the cancelled touch event (or something similar) as happens in both Android and Windows
This was easier than it looked. Solved by adding a UIGestureRecognizerDelegate to my UIGestureRecognizer class and in the delegate I overwrote ShouldRecognizeSimultaneously to return true.
So I have this project that I took from somebody else and they have implemented this OneFingerRotationGestureRecognizer (https://github.com/melle/OneFingerRotationGestureDemo/blob/master/OneFingerRotationGestureDemo/OneFingerRotationGestureRecognizer.m) for a circular slider. Additionally, they have added a UITapGestureRecognizer on top of that, so you could tap a value within that circular slider and the value would jump to that specific one. Now the problem is, when I drag that thing just a very small amount (imagine putting your thumb onto the control and tilting left/right), then the UITapGestureRecognizer also fires! And this is a problem, because I want to be able to grab the circular slider wherever I want (there is no handle or something). And when I only drag it a little, then the value just jumps to that spot where I did that small dragging. Somehow I need to cancel that tap gesture as soon as that OneFingerRotationGestureRecognizer started registering touches. I tried what is described here: https://developer.apple.com/documentation/uikit/touches_presses_and_gestures/coordinating_multiple_gesture_recognizers/preferring_one_gesture_over_another?language=objc but didn't have any success with that :-(.
What can I do? I'm afraid the solution is so simple that I just don't see it.
I have a UIView with a bunch of subviews. Each subview can either be clicked (UITouchUpInside) or 'swiped' (UITouchDragExit) to perform a different action. Both actions work as intended separately, but since the subviews are really close together, the UITouchDragExit Control event of one view accidentally activates the UITouchUpInside of the subview above it.
In order to avoid this, I was thinking of making the subview ignore all other touches to its other subviews until the UITouchDragExit gesture is over. What would be the best way of accomplishing this? In other words how can I detect the start/end of UITouchDragExit?
Thanks in advance!
I'm rather confident [editable] UITextView's become firstResponder when a long press or tap gesture occurs within the scrollView. I want to identify where in the view this touch occured. Digging through the documentation and source code didn't yield me much. I might be going about this wrong. My concern is a race condition if I just add my own tap recognizer (how can I be sure it is called before the textView's delegate methods).
For practical clarification, I want to call two similar functions from a delegate function (editingDidBegin) but depending if they touched the left or right half of the text view, I want to call either of the two.
I have a situation where I apply an effect to a UIView when a touch begins and reverse that effect when that touch ends. So basically I am tracking touchesbegan, touchesEnded and touchesCancelled methods of UIView.
But the problem is that when the view goes out of the screen, i.e. when it or one of its parents gets removed from superview, it does not get any more touch events. Is there any way to give this "last" touchesended event to the view? Maybe if the UIView gets notified about being invisible, I can also use this event for that purpose.
Ok I am going to move the answers in comments to original question to make a good summary of important points.
The reason I am tracking touch events is that I want to apply some
nice effects such as glowing on touch start and remove those effects
on touch ending.
The reason why I can not simulate touchesEnded on removing those
views is that I do not directly remove them. Instead I remove one of
the ancestor views of them. I can not keep track of ancestor views
all the way to UIWindow, it is technically impossible I think.
Instead, framework should provide this to as an event I think.
I solved my problem by overriding -(void)willMoveToWindow:(UIWindow *)newWindow method and checking if newWindow is nil.