I added a UIPanGestureRecognizerto my UIButton. And now my when I drag a short distance with my finger after I pressed the button, the button stops being highlighted. Normally, a UIButton will stay highlighted unless you drag pretty far outside the UIButtons frame. However, with a pan gesture recognizer, now even if I drag a little bit, the button stops being highlighted.
Nothing in my code sets the buttons highlighted property to no. I even tried erasing all the code in my panning gesture recognizers action selector thing(the method that gets called whenever i pan on my button).
I also tried setting the button's highlighted property to NO in the panning gesture recognizer's action selector thing.
This kind of worked its just the highlightedness flashes. When you pan the highlighted goes away then comes back really fast, like a flash. So, this doesnt work too. Any ideas?
Gestures, by default, will cancel the touches in the views that they are linked to. So, when the touches in your button get cancelled it becomes unhighlighted. To prevent this behavior, set the cancelsTouchesInView property of your gesture to NO.
This will work
-(void) panDetected:(UIGestureRecognizer *) gesture
{
if(gesture.state == UIGestureRecognizerStateBegan)
{
yourButton.backgroundImageView.image = [UIImage imageNamed:#"your_button_highlited_image.png"];
}
else if(gesture.state == UIGestureRecognizerStateChanged)
{
}
else if(gesture.state == UIGestureRecognizerStateEnded)
{
yourButton.backgroundImageView.image = [UIImage imageNamed:#"your_button_normal_image.png"];
}
}
I have experienced the same problem. borrrden is right; to fix it, set the viewController the delegate for the gestureRecognizer, and cancel the touch if the touch is on a IUButton. First add the protocol `UIGestureRecognizerDelegate on the .h file. Then, after creating the gesture recognizer, set the view controller as its delegate:
UITapGestureRecognizer *gestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(aMethod)];
gestureRecognizer.delegate = self;
[self.view addGestureRecognizer:gestureRecognizer];
[gestureRecognizer release];
Finally override shouldReceiveTouchand cancel unwanted touches:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{
if ([touch.view isKindOfClass:[UIButton class]]) { //Do not override UIButton touches
return NO;
}
return YES;
}
Related
I'd like to detect swipe on the entire screen, however, the screen contains UIButtons, and if the user taps one of these buttons, I want the Touch Up Inside event to be triggered.
I've create a UIView on the top of my screen, and added a UIPanGestureRecognizer on it to detect the swipe, but now I need to pass the gesture through that view when I detect that it's a tap rather than a swipe.
I know how to differentiate the gestures, but I've no idea on how to pass it to the view below.
Can anyone help on that? Thanks!
Thanks for your answer. The link helped me to solve part of my problem.
I've set the buttons as subviews of my gestureRecognizer view and I can now start a swipe from one of the buttons (and continue to use the buttons as well). I managed to prevent the buttons to go to the "down" state by using the following code :
UIPanGestureRecognizer *swipe = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(swipeDetected:)];
swipe.maximumNumberOfTouches = 1;
swipe.delaysTouchesBegan =YES;
swipe.cancelsTouchesInView = YES;
[self.gestureRecognitionView addGestureRecognizer:swipe];
there is a BOOL property of UIGestureRecognizer cancelsTouchesInView. default is yes. set it to NO , and the touches will pass thru to the UIView
also have a look at the solution for this question
If you want to prevent the recognizer from receiving the touch at all, UIGestureRecognizerDelegate has a method gestureRecognizer:shouldReceiveTouch: you can use:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
// don't override any other recognizers
if (gestureRecognizer != panRecognizer) {
return YES;
}
CGPoint touchedPoint = [touch locationInView:self.someButton];
return CGRectContainsPoint(self.someButton.bounds, touchedPoint) == NO;
}
I'm trying to add a UIPanGestureController to my UITableView so I can detect whether the user is manually panning or they just gave an initial kick and watch the view scroll by itself. The reason is that I want to snap to a cell as soon as the scrolling slows down (imagine a wheel of fortune). Of course I don't want to snap when the user is panning manually.
However, I can either use the gesture controller (and set my "is scrolling manually" variables accordingly") OR scroll the view.
Using TouchBegin events instead of the gesture recognizer introduces new problems, so that's not really an option.
First I changed the table view to include the UIGestureRecognizerDelegate.
After initializing the view, I then do...
panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(panTableView:)];
[panGestureRecognizer setDelegate:self];
[self.view addGestureRecognizer:panGestureRecognizer];
I implement the Begin function, to set a BOOL:
- (BOOL)gestureRecognizerShouldBegin:(UIPanGestureRecognizer *)gestureRecognizer
{
isPanning = YES;
return NO;
}
Always returning NO should make sure that the gesture recognizer is never active, since I want (and need) to use the table view's own scroll methods.
Problem: my action "panTableView" is never called.
If I don't set the delegate, the action is called, but I can't scroll, since the gesture recognizer catches all my touches.
I already looked into the targets. After setting the delegate, the gesture recognizer's view and delegate pointers are the same as self.view, the action still targets self with the right selector.
try
- (BOOL)gestureRecognizerShouldBegin:(UIPanGestureRecognizer *)gestureRecognizer
{
isPanning = YES;
return YES;
}
and implement this
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES
}
I have a scrollview in my Main view and I have three subviews on my scrollview. And I have UIButtons in all my subviews.
Now, I want to drag those buttons from one subview to another subview (while dragging the buttons, the scrollview should not scroll).
How do I do this?
I'm not completely sure if this snippet works for this particular case (an UIControl inside a UIScrollView), but my understanding of UIResponder chain suggests me that it should :)
- (void)viewDidLoad { // or wherever you initialize your things
...
// Add swipe event to UIButton so it will capture swipe intents
UIPanGestureRecognizer *panGR = [[UIPanGestureRecognizer alloc] init];
[panGR addTarget:self action:#selector(panEvent:)];
[button addGestureRecognizer:panGR];
[panGR release];
}
- (void)panEvent:(id)sender {
button.center = [sender locationInView:self.view];
}
If this works (can't test it right now, but it did work for me in a similar situation), then you should add more code to handle the drag & drop related events (maybe disable Clip Subviews option in the UIScrollView, add the button to the new superview if the location intersects with the CGRect of the destination, return the button to the original location if it doesn't, etc).
So, what's happening in those lines? When you begin touching the UIButton, the order doesn't get to the UIScrollView because the event could follow as a touch event (handled by the UIButton), or as a pan event (handled by the UIScrollView). When you move your finger, the event is dismissed by the UIButton's responder because there's no Gesture Recognizer that knows how to proceed if the finger is moved.
But when you add a Gesture Recognizer to the UIButton who actually knows what to do when the finger is moved, everything is different: the UIButton will not dismiss the event, and the UIScrollView will never realize that there was a touch moving over it.
I hope my explanation is accurate and comprensible enough. Let me know if a) it doesn't work or b) there's something unclear.
Good luck :)
Try
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
if (allowAppDrag && [gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
return NO;
}
return YES;
}
I am struggling to get the behaviour I would like from the gesture recognisers, specifically cancelling certain gestures if others have fired.
I have a scrollView set to paging and multiple subviews in each page. I have added a touch gesture recogniser to scroll to the next or prev page if the user taps to the right or left of the page.
// Add a gesture recogniser turn pages on a single tap at the edge of a page
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapGestureHandler:)];
tapGesture.cancelsTouchesInView = NO;
[self addGestureRecognizer:tapGesture];
[tapGesture release];
and my gesture handler:
- (void) tapGestureHandler:(UIGestureRecognizer *) gestureRecognizer {
const CGFloat kTapMargin = 180;
// Get the position of the point tapped in the window co-ordinate system
CGPoint tapPoint = [gestureRecognizer locationInView:nil];
// If the tap point is to the left of the page then go back a page
if (tapPoint.x > (self.frame.size.width - kTapMargin)) [self scrollRectToVisible:pageViewRightFrame animated:YES];
// If the tap point is to the right of the page then go forward a page
else if (tapPoint.x < kTapMargin) [self scrollRectToVisible:pageViewLeftFrame animated:YES];
}
All works well, except where I have a subview on the page that has buttons in it. I want to be able to ignore the tap to turn the page if the user touches a button on the subView and I can't figure out how to do this.
Cheers
Dave
The solution that worked the best for me in the end was to use the hitTest to determine if there were any buttons underneath the location of the tap gesture. If there are then just ignore the rest of the gesture code.
Seems to work well. Would like to know if there are any gotchas with what I have done.
- (void) tapGestureHandler:(UIGestureRecognizer *) gestureRecognizer {
const CGFloat kTapMargin = 180;
// Get the position of the point tapped in the window co-ordinate system
CGPoint tapPoint = [gestureRecognizer locationInView:nil];
// If there are no buttons beneath this tap then move to the next page if near the page edge
UIView *viewAtBottomOfHeirachy = [self.window hitTest:tapPoint withEvent:nil];
if (![viewAtBottomOfHeirachy isKindOfClass:[UIButton class]]) {
// If the tap point is to the left of the page then go back a page
if (tapPoint.x > (self.bounds.size.width - kTapMargin)) [self scrollRectToVisible:pageViewRightFrame animated:YES];
// If the tap point is to the right of the page then go forward a page
else if (tapPoint.x < kTapMargin) [self scrollRectToVisible:pageViewLeftFrame animated:YES];
}
}
Apple documentation shows the answer:
- (void)viewDidLoad {
[super viewDidLoad];
// Add the delegate to the tap gesture recognizer
self.tapGestureRecognizer.delegate = self;
}
// Implement the UIGestureRecognizerDelegate method
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch: (UITouch *)touch {
// Determine if the touch is inside the custom subview
if ([touch view] == self.customSubview){
// If it is, prevent all of the delegate's gesture recognizers
// from receiving the touch
return NO;
}
return YES;
}
Of course in this case customSubview would be subview on the page that has buttons in it (or even the buttons on it)
Swift 3
Set UITapGestureRecognizer
let tap = UITapGestureRecognizer(target: self, action: #selector(Class.didTap))
tap.delegate = self
UITapGestureRecognizer delegate method:
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
return touch.view != buttonThatShouldCancelTapGesture
}
You can subclass UIView and overwrite the -touchesBegan selector, or you can play with the opaque property of the subviews to make them "invisible" to the touches (if view.opaque = NO, the view ignores touch events).
CODE
I have some code that adds a UILongPressGestureRecognizer gesture recognizer called _recognizer to a subclass of a UITableViewCell called cell:
...
UILongPressGestureRecognizer *_recognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(cellLongPressRecognized:)];
_recognizer.allowableMovement = 20;
_recognizer.minimumPressDuration = 1.0f;
[[cell contentView] addGestureRecognizer:_recognizer];
[_recognizer release];
...
The -cellLongPressRecognized: selector simply logs when the gesture ends:
- (void) cellLongPressRecognized:(id)_sender {
if (((UILongPressGestureRecognizer *)_sender).state == UIGestureRecognizerStateEnded)
ALog(#"[MyViewController] -cellLongPressRecognized: gesture ended...");
}
My console shows one log message when I tap, hold and release a cell:
[MyViewController] -cellLongPressRecognized: gesture ended...
So far, so good.
ISSUE
The issue is that the table cell's background stays selected only as long as 1.0 second, the _recognizer.minimumPressDuration property.
If I hold my finger on the device any longer than 1.0 second, the cell's background flips back from the UITableViewCellSelectionStyleBlue selection style to its usual, opaque, non-selected background.
To make sure only gesture-specific code is involved with this issue, I have disabled -tableView:didSelectRowAtIndexPath: while testing.
QUESTION
How do I keep the background selected indefinitely, flipped back only when the "long press" gesture ends?
I changed my test condition from UIGestureRecognizerStateEnded to UIGestureRecognizerStateBegan and the gesture is timed with the cell selection state change:
- (void) cellLongPressRecognized:(id)_sender {
if (((UILongPressGestureRecognizer *)_sender).state == UIGestureRecognizerStateBegan)
ALog(#"[MyViewController] -cellLongPressRecognized: gesture began...");
}
Seems counterintuitive naming the event this way, but that seems to work.