I want that when the user has two fingers touching the screen, two separate UILongPressGestureRecognizers recognize the gesture for each finger (1 recognizer for 1 finger). I could use a single UILongPressGestureRecognizer with numberOfTouchesRequired set to 2, but I need the 2 touches to be recognized independently (ex: I can release one finger and the other recognizer will remain active, which is not possible with a single gesture recognizer).
Thanks for your help.
To allow both gestures to work together, implement the following delegate method:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{
return YES;
}
To make it so that the long press has first priority, do:
[tapGesture requireGestureRecognizerToFail:longPress];
Related
I have added UIPanGestureRecognizer on the view of my UIViewController.
In this view (a calculator) are some UIButton triggered by the event .TouchUpInside.
The problem comes if I tap on the button and make a small pan at the same time (which might happen if you tap quickly a button and are moving to the next one at the same time). Then the pan gesture is triggered. I would like to avoid it when there is a tap on a button. But I would like to allow it if the tap takes too long (let say 0.3s is enough to trigger the pan gesture).
How can I achieve that?
Set the property cancelsTouchesInView of your gesture recognizer to NO.
Then your button should work properly.
You can use the delegate method like this-
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{
if ([touch.view isKindOfClass:[UIButton class]]) {
return NO;
}
return YES;
}
There is a dirty solution. You can just grab it in a UIScrollView
I have a view with button and touch-move gesture. When user touches button it becomes selected and keeps receiving touch-move events. I want to deselect the button on touch-move and pass moves to gesture.
How to cancel touch receiving on button "elegantly"?
Try the next line of code on Swift 4
youButton.touchesCancelled([], with: nil)
Works well with pan gesture reco
You need to implement the UIGestureRecognizerDelegate. Specifically this method. Then just build your logic for deciding if the gesture should receive the touch or not. If you return NO then the touch is up for grabs for the button. if you return YES the gesture to take the touch.
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
If you never even more control I think you'll need to subclass the button and takeover its hit testing.
I have a map drawn with OpenGLES, and I have a pan gesture recognizer that has maximumNumberofTouches set to 1 to pan around the map and a pinch gesture recognizer for zooming. I want to start panning once im done zooming, (one finger is lifted off the screen) but the pan gesture recognizer doesnt kick in until pinchgesturerecognizer is done which is when it detects there are no fingers on the screen. Any ideas?
It may be possible to allow both gestures to be active via the delegate method:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
// The two recognizers using the delegate (scale and rotate) should both be active.
//
return YES;
}
And keep a BOOL that tracks if the user is zooming, not allowing the code in the pan gesture to execute while that BOOL is YES. Altering the BOOL value by checking the number of touches in the touchesMoved:withEvent method (or perhaps some other UIGestureRegonizer method).
I think this should work, I do something similar in an app that allows scaling, rotating, and dragging, where dragging is only allowed when the user isn't scaling/rotating.
~Good Luck
How can I know when the finger is down and when is it up with UITapGestureRecognizer?
The documentation says I should only handle UIGestureRecognizerStateEnded as tap so it means there is UIGestureRecognizerStateBegin when finger is down, but all I get is UIGestureRecognizerStateEnded.
The code I use to register the recognizer is:
[[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tap:)]
UITapGestureRecognizer is a discrete gesture recognizer, and therefore never transitions to the began or changed states. From the UIGestureRecognizer Class Reference:
Discrete gestures transition from Possible to either Recognized
(UIGestureRecognizerStateRecognized) or Failed
(UIGestureRecognizerStateFailed), depending on whether they
successfully interpret the gesture or not. If the gesture recognizer
transitions to Recognized, it sends its action message to its target.
(Remembering of course that UIGestureRecognizerStateRecognized == UIGestureRecognizerStateEnded).
The docs are saying that you should check the state of a tap gesture recognizer to see that it is in its ended state, before you fire your code to say that it has been recognized. They are not saying that the tap gesture actually transitions to the began or changed states (although I admit that the docs are a little misleading in the language used!).
If you want to check for the finger down event for a tap gesture recognizer, I would recommend just using touchesBegan:withEvent:, since this is what you are really after anyway.
You could override the delegate method -(BOOL)gestureRecognizer:shouldReceiveTouch:.
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
NSLog(#"Hello from press down");
return YES;
}
I need have a view where users can draw multiple rectangles. Now I need to be able to move those rectangles using a Pan gesture. The problem I am having is that I can move any single rectangle with the Pan gesture recognizer with no problem. Now when I use 2 fingers to Pan 2 rectangles to move simultaneously it doesn't work.
Seem to me that the problem is the target/action that I specified for the pan gesture gets fired only once.
My view adopts the UIGestureRecognizerDelegate and has defined this delegate method:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}
Thanks in advance!
Add gesture recognizer to each created rectangle view individually by making a method.
like this
- (void)addGestureRecognizersToPiece:(UIView *)piece
{
// Add the gesture recognizer to the piece here
}
You can loop in to add the gesture recognizer to all the pieces simultaneously, or while u create each rectangle, just fire this method after creating the rectangle, and passing that as the piece parameter to this function.
That should help.