iOS Detect User Touch Release - ios

This may have been posted here somewhere but I can't find it. I am writing a simple iOS app with two UIViews. The user will first press and hold a certain area of the screen then release their touch on it then quickly touching a second view below.
The first UIView has a UILongPressGestureRecognizer attached to it and works fine. The second UIView has a UITapGestureRecognizer attached to it and also works fine. I cannot however, get either of these gesture recognizers to return anything that states that the user released their touch.
I have tried this code to no avail:
- (void)holdAction:(UILongPressGestureRecognizer *)holdRecognizer
{
if (UIGestureRecognizerStateRecognized) {
holdLabel.text = #"Holding Correctly. Release Touch when ready.";
holdView.backgroundColor = [UIColor greenColor];
} else if (UIGestureRecognizerStateCancelled){
holdLabel.text = #"Ended";
holdView.backgroundColor = [UIColor redColor];
}
Any suggestions would be great and especially if someone knows how to implement a call that returns the state of a user touching the device. I've looked over the developer docs and have come up empty.

After tinkering for a couple hours, I found a way that is working, not sure if its the best way to do it. Turns out I need to be writing it like the code below. I wasn't calling the specific UIGestureRecognizer I was declaring in the viewDidLoad() method.
- (void)holdAction:(UILongPressGestureRecognizer *)holdRecognizer
{
if (holdRecognizer.state == UIGestureRecognizerStateBegan) {
holdLabel.text = #"Holding Correctly. Release when ready.";
holdView.backgroundColor = [UIColor greenColor];
} else if (holdRecognizer.state == UIGestureRecognizerStateEnded)
{
holdLabel.text = #"You let go!";
holdView.backgroundColor = [UIColor redColor];
}
}

You need to use manual touch handling here (as opposed to using a gesture recognizer). Any UIResponder subclass can implement the following four methods:
– touchesBegan:withEvent:
– touchesMoved:withEvent:
– touchesEnded:withEvent:
– touchesCancelled:withEvent:
By using these methods, you get access to every phase of the touch events. You might have to implement your own logic to detect the long press, but you have full access to all touches.
For more information on touch handling, this session from WWDC 2011 is golden (requires dev account):
https://developer.apple.com/itunes/?destination=adc.apple.com.8270634034.08270634040.8367260921?i=1527940296

Swift 4+
let gesture = UILongPressGestureRecognizer(target: self, action: #selector(self.checkAction))
self.view.addGestureRecognizer(gesture)
#objc func checkAction(sender : UILongPressGestureRecognizer) {
if sender.state == .ended || sender.state == .cancelled || sender.state == .failed {
}
}

Related

TouchesBegan delay on left hand side of the display

On iPhone's with 3D touch enabled, there is a feature where long pressing the left hand side of the screen with enough force opens lets you change which app is active. Because of this, when a non-moving touch happens on the left hand side of the screen, the touch event is delayed for a second or two until the iPhone verifies that the user is not trying to switch tasks and is interacting with the app.
This is a major problem when developing a game with SpriteKit, as these touches are delayed by a second every time a user taps/holds their finger on the left edge of the screen. I was able to solve this problem by registering a UILongPressGestureRecognizer in the main Scene of the game, thus disabling TouchesBegan and implementing a custom touches function (used as a selector by the gesture recognizer):
-(void)handleLongPressGesture:(UITapGestureRecognizer *)gesture {
CGPoint location = [gesture locationInView:self.view];
if (gesture.state == UIGestureRecognizerStateBegan)
{
//
}
else if (gesture.state == UIGestureRecognizerStateChanged)
{
//
}
else if (gesture.state == UIGestureRecognizerStateEnded)
{
//
}
else if (gesture.state == UIGestureRecognizerStateCancelled)
{
//
}
}
-(void)didMoveToView:(SKView *)view {
/* Setup your scene here */
UILongPressGestureRecognizer *longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(handleLongPressGesture:)];
longPressGestureRecognizer.delaysTouchesBegan = false;
longPressGestureRecognizer.minimumPressDuration = 0;
[view addGestureRecognizer:longPressGestureRecognizer];
// continue
}
The problem with this is that I would have to implement a gesture recognizer for every touch (including simultaneous ones) that I expect the user to enter. This interferes with any touchesBegan methods as subclasses of SKSpriteNode, SKScene, etc. and kills a lot of functionality.
Is there any way to disable this delay? When registering the gestureRecognizer, I was able to set delaysTouchesBegan property to false. Can I do the same somehow for my SKScene?
To see this issue in action, you can run the default SpriteKit project, and tap (hold for a second or two) near the left hand side of the screen. You will see that there is a delay between when you touch the screen and when the SKShapeNodes are rendered (as opposed to touching anywhere else on the screen).
* Edit 1 *
For those trying to find a way to get around this for now, you can keep the gesture recognizer but set its cancelsTouchesInView to false. Use the gesture recognizer to do everything you need to do until TouchesBegan kicks in (touchesBegan will receive the same touch event about a second after the gesture recognizer recognizes the touch). Once touchesBegan kicks in, you can disable everything happening in the gesture recognizer. This seems like a sloppy fix to me, but it works for now.
Still trying to find a more-or-less formal solution.
I have experienced this as an user and it is really annoying. The only thing that worked for me was to disable the 3D touch. Otherwise the left side of the touchscreen is almost useless.

Disable user interaction on one UIView as the other UIView is swiped

Before any starts, I understand yourView.userInteractionEnabled = NO; is an option, but let me explain first the circumstance.
I have these 2 UIView objects, stoneOne and stoneTwo. I have 4 UISwipeGestureRecognizer objects attached to them for up, down, left and right. Imagine swiping these 'stones' around a 5x5 grid.
What I don't want is to be able to swipe both at the same time.
Currently, that bug is still an issue. I'll show you a method called swipeLeft: which represents the layout for all swipe directions.
- (IBAction)swipeLeft:(UISwipeGestureRecognizer *)recognizer {
_oldMove1 = _move1;
_oldMove2 = _move2;
if (recognizer.view == _oneStone
&& recognizer.direction == UISwipeGestureRecognizerDirectionLeft) {
_twoStone.userInteractionEnabled = NO;
_oneStone = recognizer.view;
[self moveOne:CGPointMake(-1, 0) withView:_oneStone];
self.move1++;
// 'causeADelay:' runs _twoStone.userInteractionEnabled = YES;
[self performSelector:#selector(causeADelay:) withObject:_twoStone afterDelay:1];
} else if (recognizer.view == _twoStone
&& recognizer.direction == UISwipeGestureRecognizerDirectionLeft) {
_oneStone.userInteractionEnabled = NO;
_twoStone = recognizer.view;
[self moveTwo:CGPointMake(-1, 0) withView:_twoStone];
self.move2++;
[self performSelector:#selector(causeADelay:) withObject:_oneStone afterDelay:1];
}
self.moveCount++;
}
One of the things I tried was creating a delay on when I can interact with my UIView objects. This worked ONLY IF I waited a split half-second to interact. The full delay would occur, and everything would work.
My bug is when you swipe them both at the same time. Is that because of the swipe gestures attached to them?
I also tried removing and reapplying the objects as subviews...didn't work, obviously. I really need this to work otherwise I have a dead-end game. I was very new to coding when I first started and never thought about Cocos2d or other game-driven platforms for development, so everything I have came from on-the-fly thinking.
There are several solutions, but here's a particularly easy one:
Remove the swipe gesture recognizers from the stones and attach them instead to the common superview of the stones. This solves the problem, because only one gesture recognizer on the same view will recognize at any one time.
Of course, you will now have to use hit-testing to find out which stone (if any) is being swiped. But that's an easy implementation detail, and is a small price to pay.
And of course another cool feature is that you now only need four gesture recognizers total!

`touchesBegan:withEvent:` is delayed at left edge of screen

I'm experiencing an issue where the first call to touchesBegan:withEvent: on a UIView or UIViewController is delayed when you touch on the left edge of the screen. This seems to be a new issue with iOS 10, and only happens on devices with 3D Touch (iPhone 6s and newer). In fact, if you disable 3D Touch in General->Accessibility, the issue goes away.
However, the issue doesn't seem to happen when you use UIGestureRecognizers. My workaround at the moment is to create a UIGestureRecognizer subclass that overrides the touches* methods and forwards them to my old implementation.
Is this just a bug or is there a way to get rid of the delay?
try adding this to the viewdidappear method. this might fix the issue. it happened with me as well but i got this code from stack overflow that fixed my issue. hope it helps you too
let window = view.window!
let gr0 = window.gestureRecognizers![0] as UIGestureRecognizer
let gr1 = window.gestureRecognizers![1] as UIGestureRecognizer
gr0.delaysTouchesBegan = false
gr1.delaysTouchesBegan = false
Like danialias I'm working on a game. The solution I found (currently working, tested on an iPhone with 3D Touch enabled, where this was a real issue up to this point..) works for both games/apps:
It seems that UITapGestureRecognizer doesn't suffer from this delay, so simply add one to your view, and use it to handle taps.
In my game, I store touches and handle them on every interval update, so I overrode
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
and there I stored the UITouch instance and returned NO.
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
[self.touches addObject:touch];
return NO;
}
Purteeek solution seems to work nicely in my case too. This is an objective-C implementation for SpriteKit:
- (void)didMoveToView:(SKView *)view {
UIGestureRecognizer* gr0 = view.window.gestureRecognizers[0];
UIGestureRecognizer* gr1 = view.window.gestureRecognizers[1];
gr0.delaysTouchesBegan = false;
gr1.delaysTouchesBegan = false;
}
This doesn't mess with other gesture recognizers, and the system 3D Touch still works fine. I wonder why this is not the default behavior.
in iOS 13.2. it seems that trick is not possible:
[Warning] Trying to set delaysTouchesBegan to NO on a system gate gesture
recognizer - this is unsupported and will have undesired side effects
Looks like the only solution is disable 3D touch in Settings.
This works for me
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if let window = view.window,
let recognizers = window.gestureRecognizers {
recognizers.forEach { r in
r.delaysTouchesBegan = false
r.cancelsTouchesInView = false
r.isEnabled = false
}
}
}

Using gesture recognizers that dynamically stick to one touch among many

I have a view with four pan gestures attached. The first has both max and min number of touches set to 1, the second to 2, etc. This makes it so each will only recognize one touch while up to four fingers slide around on the screen.
That's working dandy. What isn't working is detecting when individual touches end. Anything I have set to happen when a gesture ends only happens when all gestures have ended completely.
Example delegate method:
- (void) handlePan:(UIPanGestureRecognizer*)recognizer {
//Setting what happens when a gesture is recognized as beginning
if (recognizer.state == UIGestureRecognizerStateBegan) {
//...whatever happens, bunnies follow your finger or whatever
} else
//Setting what happens when a gesture ends
if ((recognizer.state == UIGestureRecognizerStateEnded) |
(recognizer.state == UIGestureRecognizerStateCancelled) |
(recognizer.state == UIGestureRecognizerStateFailed)) {
NSLog(#"end");
}
}
What should be happening is that I see "end" in the console whenever any finger is lifted. Instead, I see nothing until all fingers are lifted, at which point I see "end" repeated four times (or as many times as fingers that were on the screen).
Is there any way I can make this work the way I intend?
edit After fiddling I see that I may not be analyzing my problem correctly. The whole reason I want to detect when a gesture's touch ends is that I want to have gestures able to become active when there is more than one touch on screen, but I want each gesture to only track one touch itself. I was setting an "active" flag on gestures that were tracking touches, and then toggling that flag off after touches ended, and that wasn't working, because touch-end-detection was hard to implement well.
But if there's a different way to achieve the same thing, that's the real thing I'm looking for: among many overlapping touches, have each gesture recognizer track one and only one.
You may want to do something like - it catches the change in fingers on the screen for the given gesture; you may need to add some more logic surrounding which gesture you're working with:
switch( recognizer.numberOfTouches ) {
case 1: {
NSLog(#"1 ");
break;
}
case 2: {
NSLog(#"2");
break;
}
case 3: {
NSLog(#"3");
break;
}
case 4: {
NSLog(#"4");
break;
}
default: {
NSLog(#"0");
}
}
This is what eventually worked.
In short, I made a flag that flipped whenever a gesture recognizer was assigned a touch, ensuring no other recognizers accepted that touch. I also tested each recognizer to make sure it only accepted a touch when it wasn't already following a touch. So I made each touch only get assigned once, and each recognizer only accept one touch. Worked like a charm.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
//set this to no every time a new touch happens, meaning it isn't taken yet.
touchTaken = NO;
}
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
//If the touch is taken or the gesture's already following a touch, say no.
if (touchTaken | ([gestureRecognizer numberOfTouches] > 0)) {
return NO;
}
else {
touchTaken = YES;
return YES;
}
}

How to prefer tap gesture over draw gesture?

In my view I'm overriding all the "touches*" methods to let the user draw on the screen. I'm recording the locations.
In addition I have two gesture recognizers on my view to detect single tap and double tap.
If I now move my finger just a little bit and short enough, I will be recording a small "draw" gesture. However when raising the finger, an additional tap gesture will be triggered.
By trial and error I could possibly figure out a minimum time and movement threshold but I'm sure there are smarter ways?
I need to know after how much movement and/or it is save to assume that no tap gesture will trigger.
You can avoid tap gestures. Instead of that you can recognize taps in touch events itself.
- (void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event {
if(touches.count == 1)
{
if([[touches anyObject] tapCount] == 1)
{
// Do the action here for single tap
}
else if([[touches anyObject] tapCount] == 2)
{
// Do the action here for double tap
}
}
}
And you have to set a global bool variable for check whether user moved the finger on the screen.
BOOL _isMoved;
And make it TRUE in the touch move event
- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
_isMoved = YES;
}
Before recording the track, you check whether this flag is TRUE or not? And also dont forget to make the flag to FALSE after saving the track
Hope this will help you :)

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