I am using the word "subservient" as I don't know the correct term. I have tried various things to make the my UIScrollView the last gesture to be checked, so that gestures that belong to subviews of the scroll view will fire before or instead of the scrollview.
For example I have a scroll view that contains a subview, which has a pan gesture recognizer. When I try to pan, sometimes the scroll view's pan fires, sometime the sub view's pan gesture fires. I want the subview's gesture to fire consistently instead of the scroll view if that view is directly dragged.
Did you try setting the "delaysContentTouches" property of scrollview to true?
Or you can subclass UIScrollVeiw and override the touchesShouldCancelInContentView: method like this:
-(BOOL)touchesShouldCancelInContentView:(UIView *)view
{
if ([view isKindOfClass:[UIButton class]]) {//or whatever class you want to override
return YES;
}
if ([view isKindOfClass:[UIControl class]]) {
return NO;
}
return YES;
}
Related
Using UIPanGestureRecognizer & UITapGestureRecognizer on top-level UIView.
The setup in Interface Builder:
ViewController (our main view controller)
UIView (our main view and wired to our UIViewController
Our core UIView has a subview called a “Block” which is simply a UIView.
The Block view has 4 subviews (children) each being an instance of a UIButton.
The UIButton has its Touch Up Inside event wired to the the UIViewController.
The UIView (our main top-level UIView) has a UIPanGestureRecognizer and a UITapGestureRecognizer
Here is the scenario we are trying to accomplish (a.k.a.The behavior):
A user taps a button (a cell).
The button will change its stated from “normal” to “selected”. (This works fine and the code is simple)
With a selected item, a user can place their finger anywhere on the screen an move it up or down
The issue:
Need to know when panning stops.
The top UIView does not receive a gesture stated of ended.
The UIView does not receive a touchesEnded event.
How do you know when the user has lifted their finger? Suppose I start the panning when my finger is over a UIButton, while panning occurs, the UIButton eats the touches begin and end events. Therefore, you have no way of knowing when the user stopped moving their finger across the iPhone/iPad glass.
First implement UIGestureRecognizerDelegate in your view controller.
Then set the delegate on your gesture recognizers to self and implement the following method
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}
Your target method should look like this:
-(void)gestureRegognized:(UIGestureRecognizer*)gestureRecognizer
{
if ([gestureRecognizer isMemberOfClass:[UIPanGestureRecognizer class]])
{
//check its state
if(gestureRecognizer.state==UIGestureRecognizerStateBegan)
{
// add your code here
}
else if(gestureRecognizer.state==UIGestureRecognizerStateEnded)
{
// pan gesture ended code goes here
}
}
else if([gestureRecognizer isMemberOfClass:[UITapGestureRecognizer class]])
{
if(gestureRecognizer.state!=UIGestureRecognizerStateFailed)
{
// tap gesture detected
}
}
}
I have a UIView which has two subviews, one is a UIScrollView and the other is a container view for a few other subviews. The container view is covering the scroll view completely.
Views that need to handle gestures:
UIScrollView - should handle the default pinch and pan gestures
Container view - none
Container view subviews - should handle tap gesture
Now in order for the tap gestures to be handled by the container view subviews I implemented pointInside:withEvent: for the container view. If it recognises the point is inside one of its subviews it returns YES. This works fine. The problem is that when I pinch or pan and my finger initially touches one of the container view subviews it doesn't work. When I pinch or pan on an empty area of the container view it works as it should.
Any suggestions how to make it work?
EDIT:
I've implemented hitTest:withEvent: for the main view and got the same behavior.
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
UIView *hitTestView;
for (UIView *subview in [self.subviews reverseObjectEnumerator])
{
hitTestView = [subview hitTest:[self convertPoint:point
toView:subview]
withEvent:event];
if (hitTestView && ![hitTestView isKindOfClass:[ContainerView class]])
{
break;
}
}
return hitTestView;
}
On the bottom line the question here is how does one view only handles some gestures and passes on other gestures so an underlying view could handle them.
I've read quite a lot about the subject and tried different approaches but couldn't find a straightforward solution to what seems like a pretty common issue.
You don't actually need to handle pinch and pan gesturese on UIScrollView manually, it's going to happen automatically.
For handling container view subviews you can use UITapGestureRecognizer. For each view you need to handle tap use:
UITapGestureRecognizer* tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTapFirstSubview:)];
[firstSubview addGestureRecognizer:tapRecognizer];
Handler method:
- (void)handleTapFirstSubview:(UITapGestureRecognizer *)tapRecogmizer
{
// handle tap here
}
I have a custom UICollectionViewCell that has a few custom UIView objects residing inside them. Each of these UIViews has a UIButton which responds to Touch Down and Touch Up Inside linked by IBActions. Basically, I want these buttons to shrink down when pressed down and spring back to their original size when let go. I can easily accomplish this with the controls and the press down and press up works. However, the problem I am facing happens when scrolling is introduced into the mix. The UICollectionView these cells are apart of is a scrolling one. If I happen to touch a button as I start my scroll, the Touch Down event is triggered as well as the scrolling event of the UICollectionView. If I recall correctly, this was never the case pre-iOS7. When a scrolling event was started, the UIButton event wasnt fired off, I think it had to do with the delaysContentTouches. This looks to be broken or changed now. It actually still works decently on iPhone, just not on iPad. If I scroll my view on iPad, with my touch starting inside the embedded UIButton, the button will shrink and the buttons action will be fired off.
So to restate the issue as plainly as I can: Is there anyway to ignore touches on embedded UIButtons when scrolling is occurring? Touches work fine when there is no scrolling triggered, I just dont want the events to fire off if the user is indeed scrolling. Is there any workaround?
If you need any more specific details, I would be happy to help you understand.
you need to subclass scrollView (collectionView or tableView) and override
- (BOOL)touchesShouldCancelInContentView:(UIView *)view {
if ([view isKindOfClass:UIButton.class]) {
return YES;
}
return [super touchesShouldCancelInContentView:view];
}
swift
override func touchesShouldCancelInContentView(view: UIView) -> Bool {
if view is UIButton {
return true
}
return super.touchesShouldCancelInContentView(view)
}
thats it now you can scroll over button and not lose button tap event.
In a UICollectionView of mine, buttons inside of UICollectionViewCells registered TouchUpInside-taps even though the UICollectionView was still decelerating, which sounds like a similar problem to what you're having. I created a UIButton subclass that overrides beginTrackingWithTouch:withEvent and will return NO in case the UIScrollView it's contained in is decelerating or dragging.
- (BOOL)beginTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event
{
UIView *superView = self;
while((superView = [superView superview])) {
if ([superView isKindOfClass:UIScrollView.class]) {
UIScrollView *scrollView = (UIScrollView *)superView;
if (scrollView.isDecelerating || scrollView.isDragging) {
return NO;
}
}
}
return [super beginTrackingWithTouch:touch withEvent:event];
}
The easiest thing to try that comes to mind is to check if the UIScrollView (your UICollectionView) is scrolling or dragging when the button action is triggered.
if(! self.collectionView.dragging && ! self.collectionView.decelerating)
{
// do action because we are not moving
}
Have you tried that?
I'm building an iOS app that has a custom UIView upon a UIScrollView which in turn has a subview.
Here's the layout structure:
Note that the custom UIView(called "Detected Object Hint View") is not a subview of ScrollView, it's a sibling view of UIScrollView. And I want to respond to tap gesture on the custom UIView, so I've added UITapGestureRecognizer to the UIView, and it works for tap, but the UIScrollView will never get any touch events (not responding to scroll or zoom gesture).
I've googled a while, and a lot of people pointed out that in order for other view to respond to the touch events, I should implement the following method:
- (id)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
UIView *hitView = [super hitTest:point withEvent:event];
if (hitView == self){
return nil;
}
else {
return hitView;
}
}
But once I've added this method to my custom UIView, it will not respond to tap gesture either (of course).
So I'm wondering how can I handle the tap gesture on my custom UIView and pass the touch events to UIScrollView as well?
Big thanks!
I am hoping someone will be able to help me with a problem that is doing my head in at the moment!
Given the following view hierarchy
I want to be able to detect swipe gestures on my custom UITableViewCell.
I have subclassed the UIScrollView and have a hitTest:withEvent: method that checks whether I am touching the tableview cell (or its content) or not, in which case I set the following scroll view properties:
- (UIView*)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
UIView* result = [super hitTest:point withEvent:event];
if ([result.superview isKindOfClass:[UITableViewCell class]] || [result.superview tag] == SUBVIEW_TAG)
{
self.canCancelContentTouches = NO;
self.delaysContentTouches = YES;
} else {
self.canCancelContentTouches = YES;
self.delaysContentTouches = NO;
}
return result;
}
I have also implemented:
- (BOOL)touchesShouldCancelInContentView:(UIView *)view
{
if (view.tag == SUBVIEW_TAG || [[view superview] isKindOfClass:[UITableViewCell class]])
return NO;
return YES;
}
And am returning NO in case the view being touched is the table view cell.
These methods are all getting called and performing their actions as expected, but I am still unable to stop the UIScrollView from "hogging" the swipe gesture.
The interesting thing is that if I include the UIView that contains the tableview and cell on both of the methods above (the one with SUBVIEW_TAG) it works perfectly so I am guessing it must be something to do with the fact that UITableView inherits from UIScrollView.
My main goal is to be able to swipe on the cell to reveal more options for the cell. A horizontal swipe anywhere else on that view would be captured by the scroll view and shift the content horizontally as per its normal behaviour.
Any ideas would be very much appreciated!
Thanks!
Rog
I had a similar problem with a swipe detect for a component inside a scrollview and I was able to resolve it with
[scrollView.panGestureRecognizer requireGestureRecognizerToFail:swipeGesture]
Where scrollView is the scroll view object that acts like container and swipeGesture is the component swipe gesture object inside scrollview.
So, you can define a swipe for the cell object like this (for right swipe in the example, custom it as you want)
UISwipeGestureRecognizer* rightSwipeRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(yourMethod)];
[rightSwipeRecognizer setDirection:UISwipeGestureRecognizerDirectionLeft];
[cell addGestureRecognizer:rightSwipeRecognizer];
and then do
[scrollView.panGestureRecognizer requireGestureRecognizerToFail:rightSwipeRecognizer]
The documentation of requireGestureRecognizerToFail says:
This method creates a relationship with another gesture recognizer
that delays the receiver’s transition out of
UIGestureRecognizerStatePossible. The state that the receiver
transitions to depends on what happens with otherGestureRecognizer:
If otherGestureRecognizer transitions to
UIGestureRecognizerStateFailed, the receiver transitions to its normal
next state.
if otherGestureRecognizer transitions to
UIGestureRecognizerStateRecognized or UIGestureRecognizerStateBegan,
the receiver transitions to UIGestureRecognizerStateFailed.
An example where this method might be called is when you want a
single-tap gesture require that a double-tap gesture fail.
Availability Available in iOS 3.2 and later.
Hope helps!
The solution is pretty simple. All you need to do is add UIScrollView inside you UITableViewCell. It will prevent "hogging" effect during swipe gesture.