I have two views one beneath the another. I'm rotating the below view by touch sensing of top view. while trying to make a swipe, touches canceled event is called before touches ended event. While moving the finger touches began and touches moved events are called , and then touches ended event is called at the last(mostly). But sometimes while trying to move slowly,touches canceled event is called stopping the touch events to occur. So i couldn't rotate view in slow speed. What may be the problem? how to avoid touches canceled event?
Note: I'm drawing some graphs in views using core-plot lib.
If you are using any UIGestureRecognizers they automatically cancel touches to other views when they recognize their gesture. You can turn this behavior off with the cancelsTouchesInView property of the recognizer.
If your are not using UIGestureReconizer directlly, be aware of the property gestureRecognizers of the UITouch.
I have the same problem and with this code I solve it:
if (event.type == UIEventTypeTouches)
{
NSSet* tmpTouches = [event touchesForView:m_PhotoView];
if ([tmpTouches count] == 2)
{
UITouch *tmpTouch1 = [[tmpTouches allObjects] objectAtIndex:0];
UITouch *tmpTouch2 = [[tmpTouches allObjects] objectAtIndex:1];
if ((tmpTouch1 != nil)&&(tmpTouch2 != nil))
{
UIGestureRecognizer * tmpG;
if ([tmpTouch1.gestureRecognizers count] > 0)
{
tmpG = [tmpTouch1.gestureRecognizers objectAtIndex:0];
tmpG.cancelsTouchesInView = NO;
}
if ([tmpTouch2.gestureRecognizers count] > 0)
{
tmpG = [tmpTouch2.gestureRecognizers objectAtIndex:0];
tmpG.cancelsTouchesInView = NO;
}
// Code ...
}
}
}
Look out for UISwipeGestureRecognizer as well. This was causing the issue for me and is resolved once we set
[recognizer setCancelsTouchesInView:FALSE];
If a scroll view is involved, uncheck its property content touch Can Cancel On Scroll in the storybord.
Related
The player drags a sprite in my game but when accidentally touch the screen with a second finger it screws the movement obviously.
I used the following solutions for disable the second touch, but unfortunately it doesn't work:
//--------------
-(void)touchesBegan:(NSSet*) touches withEvent:(UIEvent*) event {
if (touches.count == 1 && draggedNode == nil) {
CGPoint pos = [[touches anyObject] locationInNode:self];
SKNode * touchedNode = [self nodeAtPoint:pos];
if([touchedNode.name isEqual: #"shooterBall"]){
draggedNode = touchedNode;
}
draggedNodeOffset = CGPointMake(draggedNode.position.x - pos.x, draggedNode.position.y - pos.y);
}
}
//--------------
-(void)touchesMoved:(NSSet*) touches withEvent:(UIEvent*) event {
if (touches.count <= 1) {
CGPoint pos = [[touches anyObject] locationInNode:self];
draggedNode.position = CGPointMake(pos.x + draggedNodeOffset.x, pos.y+draggedNodeOffset.y);
}
}
//--------------
-(void)touchesEnded:(NSSet*) touches withEvent:(UIEvent*) event {
draggedNode = nil;
}
//--------------
Do you have any solution for this?
Thanks your help in advance!
You want to implement UIPanGestureRecognizer in your scene. It will allow you to track the location of the user's touch and at the same time control other "stray" touches: UIPanGestureRecognizer Documentation
After you initialize it, you need to implement a method to handle the user's pans. You will have to set flags inside of this method to control when the swipe started/ended. I think this answer on StackOverflow gave a really good explanation of using it (with Swift). BTW, when you initialize it, you should set the gesture recognizer's property maximumNumberOfTouches to 1 (that will cause it to ignore other touches while the user is panning).
The trickier part will be to translate the same code you wrote before to gesture recognizer. The difference is that your handler will be called only once for each "swipe" or "pan", while the touches method you are using now is called each time there is a "touch". There are a few ways to proceed at this point, and you could try whatever you like, but I think that this would be the easiest way to go once you have your gesture recognizer set up (spoiler):
make sure the gesture recognizer is an instance variable so you can access it from all methods.
go to the update: method and make an if statement that checks if gesture.state == UIGestureRecognizerStateBegan || gesture.state == UIGestureRecognizerStateChanged
use the same algorithm that you had before in this if statement. To check the location that the touch is at use the method: locationInView:. Use self.view as the parameter.
Hope this helped! good luck.
So my current project has a pan gesture recognizer, and if I have panned to the top of the screen the screen it is supposed to scroll up to account for that gesture. While the gesture hasn't ended and the current position of the gesture remains at the top of the screen, I want to continually keep scrolling. My problem is the gesture recognizer only gets called when the state changes, therefore my content will only scroll if you move back and forth at the top, not continually while the gesture continues to be at the top. Is there any reasonable way to continually call code while the gesture hasn't ended, but isn't necessarily changing? Here is pseudo-code of what I have:
- (void)handleGestureRecognizer:(UIGestureRecognizer *)gesture {
if ( gesture.state == UIGestureRecognizerStateChanged ) {
CGPoint point = [gesture locationInView:self.view];
if (point.y < 100) {
//I would like this code to be called continually while the
//gesture hasn't ended, not necessarily only when it changes
[self updateScrollPosition];
}
}
I can think of a few ghetto ways to do it by setting state bools based on the current state of the recognizer and creating my own timer to periodically check, but it seems pretty hacky and I don't particularly like it, so I'm wondering if anyone could come up with a cleaner solution.
One way to use a timer and feel better about it would be to conceal it a little by using performSelector:withObject:afterDelay:
- (void)stillGesturing {
[self updateScrollPosition];
[NSObject cancelPreviousPerformRequestsWithTarget:self];
[self performSelector:#selector(stillGesturing) withObject:nil afterDelay:0.5];
}
// then in the recognizer target
if (gesture.state == UIGestureRecognizerStateEnded) {
[NSObject cancelPreviousPerformRequestsWithTarget:self];
} else if ( gesture.state == UIGestureRecognizerStateChanged ) {
CGPoint point = [gesture locationInView:self.view];
if (point.y < 100) {
//I would like this code to be called continually while the
//gesture hasn't ended, not necessarily only when it changes
[self stillGesturing];
}
}
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;
}
}
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 :)
I am using a UIPinchGestureRecognizer, which uses 2 fingers by default. If a user decides to perform the multitask gesture, the pinch gestures action is also activated.
Is there a way to cancel the pinch gesture from occurring if more than four UITouch instances are detected?
Edit Removed sample code as it was the wrong approach.
Since you're not subclassing the UIPinchGestureRecognizer, you shouldn't be using touchBegan:withEvent:. Instead you should be handling it in the method that is called when a pinch occurs.
- (void)handlePinch:(UIPinchGestureRecognizer *)pinchGestureRecognizer
{
// if there are 2 fingers being used
if ([pinchGestureRecognizer numberOfTouches] == 2) {
// do stuff
}
}
With a multitask gesture, the numberOfTouches returned by the UIPinchGestureRecognizer is 2 instead of 4 or 5, because some touches are ignored.
You can subclass UIPinchGestureRecognizer and override ignoreTouch:forEvent to cancel the recognizer if the event has 4 or 5 touches:
- (void) ignoreTouch:(UITouch*)touch forEvent:(UIEvent*)event
{
[super ignoreTouch:touch forEvent:event];
// Cancel recognizer during a multitask gesture
if ([[event allTouches] count] > 3)
{
self.state = UIGestureRecognizerStateCancelled;
}
}