UILongPressGestureRecognizer gets called twice when pressing down

Question

I am detecting if the user has pressed down for 2 seconds:

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
                                             initWithTarget:self 
                                             action:@selector(handleLongPress:)];
        longPress.minimumPressDuration = 2.0;
        [self addGestureRecognizer:longPress];
        [longPress release];

This is how I handle the long press:

-(void)handleLongPress:(UILongPressGestureRecognizer*)recognizer{
    NSLog(@"double oo");
}

The text "double oo" gets printed twice when I press down for longer than 2 seconds. Why is this? How can I fix?

score 729 · Accepted Answer · edited Apr 04 '15 at 02:09

729

UILongPressGestureRecognizer is a continuous event recognizer. You have to look at the state to see if this is the start, middle or end of the event and act accordingly. i.e. you can throw away all events after the start, or only look at movement as you need. From the Class Reference:

Long-press gestures are continuous. The gesture begins (UIGestureRecognizerStateBegan) when the number of allowable fingers (numberOfTouchesRequired) have been pressed for the specified period (minimumPressDuration) and the touches do not move beyond the allowable range of movement (allowableMovement). The gesture recognizer transitions to the Change state whenever a finger moves, and it ends (UIGestureRecognizerStateEnded) when any of the fingers are lifted.

Now You Can Track The State Like This

-  (void)handleLongPress:(UILongPressGestureRecognizer*)sender { 
    if (sender.state == UIGestureRecognizerStateEnded) {
      NSLog(@"UIGestureRecognizerStateEnded");
    //Do Whatever You want on End of Gesture
     }
    else if (sender.state == UIGestureRecognizerStateBegan){
       NSLog(@"UIGestureRecognizerStateBegan.");
   //Do Whatever You want on Began of Gesture
     }
  }

edited Apr 04 '15 at 02:09

Crashalot

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answered Jul 23 '10 at 16:41

joelm

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The next answer down shows how to do it, but I gave this answer the +1 because of its detailed explaination and link to documentation. – Matt Connolly Mar 23 '11 at 01:13
2

Could be more helpful with a code example, rather than linking just to the documentation. I have posted my code snippet below. check the UIGestureRecognizerStateBegan state. – Paul Solt Aug 18 '11 at 20:58
UIGestureRecognizerStateChanged – Rajneesh071 Mar 12 '13 at 14:17
@joelm you saved me ) – Evgeniy Kleban Nov 01 '17 at 05:43
For Swift 4: if (sender.state == UITapGestureRecognizer.State.ended ) { //Do Whatever You want on End of Gesture print("\n * longpressed *\n") } – Ravi Oct 11 '18 at 06:58

score 123 · Answer 2 · edited Jan 17 '17 at 22:22

123

To check the state of the UILongPressGestureRecognizer just add an if statement on the selector method:

- (void)handleLongPress:(UILongPressGestureRecognizer *)sender {    
    if (sender.state == UIGestureRecognizerStateEnded) {
        NSLog(@"Long press Ended");
    } else if (sender.state == UIGestureRecognizerStateBegan) {
        NSLog(@"Long press detected.");
    }
}

edited Jan 17 '17 at 22:22

shim

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answered Nov 11 '10 at 15:43

Dan

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You don't want that if/else block, since there are more states than Ended. "Long press detected" will print multiple times when the state changes. Check the UIGestureRecognizerStateBegan state instead. – Paul Solt Aug 18 '11 at 20:59
2

Someone should really edit that answer to fit with what the top comment says. As it stands the code provided does not work. – Declan McKenna Sep 11 '12 at 22:40

Paul Solt · Answer 3 · 2018-06-14T21:06:36.060

86

You need to check the correct state, since there are different behaviors for each state. Most likely you're going to need the UIGestureRecognizerStateBegan state with the UILongPressGestureRecognizer.

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
                                             initWithTarget:self 
                                             action:@selector(handleLongPress:)];
longPress.minimumPressDuration = 1.0;
[myView addGestureRecognizer:longPress];
[longPress release];

...

- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture {
    if(UIGestureRecognizerStateBegan == gesture.state) {
        // Called on start of gesture, do work here
    }

    if(UIGestureRecognizerStateChanged == gesture.state) {
        // Do repeated work here (repeats continuously) while finger is down
    }

    if(UIGestureRecognizerStateEnded == gesture.state) {
        // Do end work here when finger is lifted
    }
}

edited Jun 14 '18 at 21:06

answered Aug 18 '11 at 20:55

Paul Solt

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Seems like you have to move your fingers to get the state to change; is that correct? – Arcadian Jan 18 '12 at 04:46
It might trigger StateChanged when moving fingers around, that sounds similar to what I was doing in my test code. – Paul Solt Jan 20 '12 at 04:12
1

UIGestureRecognizerStateBegan seems to only be called once which is perfect for my situation trying to show a dialog on detecting a long press on a button. The other states get called multiple times. Thanks! – Damian Mar 09 '12 at 13:29

score 20 · Answer 4 · edited Jul 12 '16 at 13:07

Just try this:

Objective-C

- (void)handleLongPress:(UILongPressGestureRecognizer*)sender { 
    if (sender.state == UIGestureRecognizerStateEnded) {
        NSLog(@"Long press Ended");
    } else if (sender.state == UIGestureRecognizerStateBegan) {
        NSLog(@"Long press detected.");
    }
}

Swift 2.2:

func handleLongPress(sender:UILongPressGestureRecognizer) {

        if (sender.state == UIGestureRecognizerState.Ended) {
            print("Long press Ended");
        } else if (sender.state == UIGestureRecognizerState.Began) {
            print("Long press detected.");
        }
}

score 18 · Answer 5 · edited Mar 12 '18 at 03:27

18

Swift 3.0:

func handleLongPress(sender: UILongPressGestureRecognizer) {

    if sender.state == .ended {
        print("Long press Ended")
    } else if sender.state == .began {
        print("Long press detected")
    }

edited Mar 12 '18 at 03:27

Pang

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answered Nov 26 '16 at 12:49

fozoglu

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score 14 · Answer 6 · answered Sep 24 '14 at 21:29

Here's how to handle it in Swift:

func longPress(sender:UILongPressGestureRecognizer!) {

        if (sender.state == UIGestureRecognizerState.Ended) {
            println("Long press Ended");
        } else if (sender.state == UIGestureRecognizerState.Began) {
            println("Long press detected.");
        }
}

score 7 · Answer 7 · edited Jul 07 '14 at 19:12

your gesture handler receives call for each state of gesture. so you need to put a check for each state and put your code in required state.

One must prefer using switch-case over if-else :

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
                                         initWithTarget:self 
                                         action:@selector(handleLongPress:)];
    longPress.minimumPressDuration = 1.0;
    [myView addGestureRecognizer:longPress];
    [longPress release];

-(void)handleLongPress:(UILongPressGestureRecognizer *)gesture {
        switch(gesture.state){
          case UIGestureRecognizerStateBegan:
               NSLog(@"State Began");
               break;
          case UIGestureRecognizerStateChanged:
               NSLog(@"State changed");
               break;
          case UIGestureRecognizerStateEnded:
               NSLog(@"State End");
               break;
          default:
               break;
         }
}

UILongPressGestureRecognizer gets called twice when pressing down

7 Answers7

Just try this:

Linked

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