I see a bunch of people asking about this on here, but I haven't seen any good solutions. Basically I want to detect when a user is done scrolling the table, and releases their finger. I don't want to do anything until their finger is off the screen or I think
scrollViewDidScroll would work. Any help would be amazing. Thanks!
UITableViewDelegate conforms to the UIScrollViewDelegate protocol, which provides the scrollViewDidEndDragging:willDecelerate: method.
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.
I've never run into this and can't seem to find anyone else talking about this. I have a simple tableview in a view controller. For some reason, the tableview doesn't allow any touches when it is moving. User can't select a cell or stop the motion of the scroll when it's scrolling. Anyone ever encountered this? Thanks in advance!
It sounds like you're doing something in a delegate method for UIScrollViewDelegate that is messing with the touch handling. Make sure you aren't blocking or doing anything otherwise weird in those methods.
So I have added a UIUITableView to a UIViewController. I can't use a UITableViewController for reasons I don't need to explain since it will be unnecessary information. Anyway, I have set the delegate, and the data source to this viewController. I've added the delegate and datasource protocols as well. The cells are populated correctly, so the datasource is working fine. I can also scroll so it all works fine.
However, I can't get the didSelectRowAtIndexPath to trigger. It SHOULD trigger, but doesn't. I've read and a lot of issues with this can be correlated to a UIGestureRecognizer, but I haven't implemented one. I also use the standard UITableView, so not a custom made one.
If I long press the cells (3-4 sec) then it gets triggered as it's supposed to. This suggests that there is some issue with another view or something absorbing the tap gesture, which I have no control over. How would I solve this?
No, it's not didDeselectRowAtIndexPath.
Yes all delegates and datasources are correct, since I can get the delegates/sources to trigger.
Yes, Single Selection is set on the TableView in the inspector.
Yes, everything has user interaction enabled.
If I just copy the code over to a UITableViewController it will work just fine, but right now that is not an option, I'm afraid. Anyone got any ideas on how to solve this? Most people who've had this issue has either had the issues in the list above, or added a UIGesture on top of the UITableView - I haven't.
I want to start by saying that I appreciate all the answers here provided, it gave me a lot of things to try out so I learned a lot - thanks! None of your suggestions worked, but simply because I'm a complete idiot. I said in the post that I did NOT implement a UIGestureRecognizerwhich I didn't...in that class, but in its super class. So I DID in fact implement it, but in a class that this ViewController was a subclass off. The only reason I didn't remember it was because I haven't looked at that super class for weeks.
Someone did suggest it in the comments that I should check for it, and I did and I was already certain I didn't implement one, so I quickly dismissed it. But now, after about 4 hours of debugging and recreating the project, adding things one by one, I eventually realized that the only thing that differed at this point was the Super Class, and the first piece of code I see when I open the file up was a GestureRecognizer...
So keep this in mind in the future everyone - I know I will. Thanks again for the help!
Sincerely,
The complete idiot.
Make sure you don't add any controller in that cell, which covers the entire cell and also the user interaction of that controller is enabled.
Due to that controller's user interaction enabled the tap action is taken by that controller and when you long press that cell, that cell will receive your tap.
Example :
UIView *_view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, _cellWidth, _cellHeight)];
[_view setUserInteractionEnabled:YES];
[cell.contentView addSubview:_view];
In the above case that view got your tap instated of the cell.
I know what I want to do, but I'm stumped as to how to do it: I want to implement something like the iOS multitasking gestures. That is, I want to "steal" touches from any view inside my view hierarchy if the number of touches is greater than, say, two. Of course, the gestures are not meant to control multitasking, it's just the transparent touch-stealing I'm after.
Since this is a fairly complex app (which makes extensive use of viewController containment), I want this to be transparent to the views that it happens to (i. e. I want to be able to display arbitrary views and hierarchies, including UIScrollViews, MKMapViews, UIWebViews etc. without having to change their implementation to play nice with my gestures).
Just adding a gestureRecognizer to the common superview doesn't work, as subviews that are interaction enabled eat all the touches that fall on them.
Adding a visually transparent UI-enabled view as a sibling (but in front) of the main view hierarchy also doesn't work, since now this view eats all the touches. I've experimented with reimplementing touchesBegan: etc. in the touchView, but forwarding the touches to nextResponder doesn't work, because that'll be the common superview, in effect funnelling the touches right around the views that are supposed to be receiving them when the touchView gives them up.
I am sure I'm not the only one looking for a solution for this, and I'm sure there are smarter people than me that have this already figured out. I even suspect it might not actually be very hard, and just maybe my brain won't see the forest for the trees today. I'm thankful for any helpful answers anyway :)
I would suggest you to try using method swizzling, reimplementing the touchesbegan on UIView. I think that the best way is to store in a static shared variable the number of touches (so that each view can increment/decrement this value). It's just a very simple idea, take it with a grain of salt.
Hope this helps.
Ciao! :)
A possible, but potentially dangerous (if you aren't careful) approach is to subclass your application UIWindow and redefine the sendEvent: method.
As this method is called for each touch event received by the app, you can inspect it and then decide to call [super sendEvent:] (if the touch is not filtered), or don't call it (if the touch is filtered) or just defer its call if you are still recognizing the touch.
Another possibility is to play with the hitTest:withEvent: method but this would require your stealing view to be placed properly in the subview, and I think it doesn't fit well when you have many view controllers. I believe the previous solution is more general purpose.
Actually, adding a gesture recognizer on the common superview is the right way to do this. But it sound like you may need to set either delaysTouchesBegan or cancelsTouchesInView (or both) to ensure that the gesture recognizer handles everything before letting it through to the child views.
This might be a stupid question, but I inserted a webview in a scroll view, and unfortunately both the scrollview and the webview don't move fluently when touched like in Safari. How can I solve this problem? Is there any way to make them scroll and zoom more fluently? Sorry for my spelling but I'm not [a native English speaker]. Thanks.
To be able to move more fluently, you can probably reduce the contents of the websites. In my experience UIWebViews are really heavy objects (memory and processor wise talking). As far as I know, Apple is been trying to achieve a better performance of the class. I can't imagine a simple solution for this problem. Even loading a single UIWebView is not that easy for the OS. But I could be wrong ...
BTW: A UIWebView already implements a UIScrollView, though it is not actually a subclass and it conforms to the UIScrollViewDelegate protocols.
UIWebView is allready a subclass of UIScrollView so you shouldn't use UIScrollView class again. Use delgete methods of UIWebView.