Sparrow Forum

1. 

   juce
   Member

   Greetings, Sparrow community!

   What is the best way to correctly handle different types of "click" events? In particular, i'm trying to have my code react differently to a single tap vs. double tap. The logic looks roughly like this:

       touches = [[event touchesWithTarget:self andPhase:SPTouchPhaseEnded] allObjects];
       if (touches.count == 1)
       {
           SPTouch *touch = [touches objectAtIndex:0];
           if (touch.tapCount == 1)
           {
               NSLog(@"clicked.");
               //...
           }
           else if (touch.tapCount == 2)
           {
               NSLog(@"double clicked!");
               //...
           }
       }

   This works, but with a caveat that when i do a double-tap, two 2 events are generated instead of one, and i see this in the log window:

   2011-10-27 09:33:09.016 MaximQuad[4232:207] clicked.
   2011-10-27 09:33:09.192 MaximQuad[4232:207] double clicked!

   Is there a way to have Sparrow only generate one event (double-tap)?
   Thanks.

   Posted 6 months ago #
2. 

   borrrden
   Moderator

   No, this is the behavior that is generated from the system. You must cancel the single click event in your double click handler.

   http://www.cimgf.com/2010/06/14/differentiating-tap-counts-on-ios/

   Posted 6 months ago #
3. 

   juce
   Member

   Ah, I see. Thanks for the explanation and the link.
   (I'm new to iOS programming, but I've heard about these so-called Gesture Recognizers... Thought maybe there was a way to use them in Sparrow)

   Posted 6 months ago #
4. 

   borrrden
   Moderator

   Gesture recognizers are for swiping, which is a lot more complicated ^^.

   Posted 6 months ago #
5. 

   Dan
   Member

   @juce you can indeed use GestureRecognizers in Sparrow and there is a UITapGestureRecognizer on which you can set the number of taps required.

   Can't quite remember how we got GestureRecognizers working in Sparrow but give it a go and see how you get on

   Posted 6 months ago #
6. 

   borrrden
   Moderator

   There IS?! I didn't know that >_<;;;

   Posted 6 months ago #
7. 

   Dan
   Member

   Yeah check it out: http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UITapGestureRecognizer_Class/Reference/Reference.html#//apple_ref/occ/cl/UITapGestureRecognizer

   There's also a list of the gestures in the UIGestureRecognizer class reference:
   http://developer.apple.com/library/ios/#DOCUMENTATION/UIKit/Reference/UIGestureRecognizer_Class/Reference/Reference.html

   Posted 6 months ago #
8. 

   Shilo
   Master Sparrow

   Gesture recognizers are very easy to use. But you can still do double tap recognizing quite easy in Sparrow, you have the right idea.

   To accomplish a single/double tap gesture in Sparrow, you would have to set a delayed invocation for the single tap event and then cancel it on a double tap.

   Example: (coding on iPhone)

   - (void)onTouch:(SPTouchEvent *)event {
       touches = [[event touchesWithTarget:self andPhase:SPTouchPhaseEnded] allObjects];
       if (touches.count == 1)
       {
           SPTouch *touch = [touches objectAtIndex:0];
           if (touch.tapCount == 1)
           {
               NSLog(@"clicked.");
               [self performSelector:@selector(onSingleTap:) withObject:touch afterDelay:0.25f];
           }
           else if (touch.tapCount == 2)
           {
               NSLog(@"double clicked!");
               [NSObject cancelPreviousPerformRequestsWithTarget:self];
               [self performSelector:@selector(onDoubleTap:) withObject:touch];
           }
       }
   }
    
   - (void)onSingleTap:(SPTouch *)touch {
       NSLog(@"single tap");
   }
    
   - (void)onDoubleTap:(SPTouch *)touch {
      NSLog(@"double tap");
   }

   Posted 6 months ago #
9. 

   Shilo
   Master Sparrow

   Gesture recognizers are very easy to use. But you can still do double tap recognizing quite easy in Sparrow, you have the right idea.

   To accomplish a single/double tap gesture in Sparrow, you would have to set a delayed invocation for the single tap event and then cancel it on a double tap.

   Example: (on iPhone)

   - (void)onTouch:(SPTouchEvent *)event {
       touches = [[event touchesWithTarget:self andPhase:SPTouchPhaseEnded] allObjects];
       if (touches.count == 1)
       {
           SPTouch *touch = [touches objectAtIndex:0];
           if (touch.tapCount == 1)
           {
               NSLog(@"clicked.");
               [self performSelector:@selector(onSingleTap:) withObject:touch afterDelay:0.25f];
           }
           else if (touch.tapCount == 2)
           {
               NSLog(@"double clicked!");
               [NSObject cancelPreviousPerformRequestsWithTarget:self];
               [self onDoubleTap:touch];
           }
       }
   }
    
   - (void)onSingleTap:(SPTouch *)touch {
       NSLog(@"single tap");
   }
    
   - (void)onDoubleTap:(SPTouch *)touch {
      NSLog(@"double tap");
   }

   Posted 6 months ago #
10. 

    juce
    Member

    Many thanks, everyone.
    Shilo, you code works very well! I was going to look into Gesture recognizers, but it seems they are indeed not necessary in this case.

    My only concern is that it then becomes a timing issue: either delay is too short and then it's possible for the user to do a "slow double-tap", which will still result in both events being processed and reacted too; or if the delay is made longer to prevent that, then the application will appear sluggish and too slow to react to single-tap events.

    That being said, i can't really think of any alternative to this overall principle of wait-and-cancel... So, perhaps it should be up to the application to avoid this kind of scenarios, or make it so that the delay is not a problem.

    Posted 6 months ago #
11. 

    enbr
    Moderator

    It's possible that gesture recognizers have better event handling so that the delay is not as noticeable and double tap speed is not an issue. You might try them and see if there is an improvement.

    Posted 6 months ago #

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