Building Your Game: Understanding Gestures and Movements - Beginning iOS6 Games Development - page 189

for (int touch=1;touch<=4;touch++){
UITapGestureRecognizer* tripleTap=[[UITapGestureRecognizer alloc] initWithTarget:self
action:@selector(tapGesture:)];
[tripleTap setNumberOfTapsRequired:3];
[tripleTap setNumberOfTouchesRequired:touch];
UITapGestureRecognizer* doubleTap=[[UITapGestureRecognizer alloc] initWithTarget:self
action:@selector(tapGesture:)];
[doubleTap setNumberOfTapsRequired:2];
[doubleTap setNumberOfTouchesRequired:touch];
[doubleTap requireGestureRecognizerToFail:tripleTap];
UITapGestureRecognizer* singleTap=[[UITapGestureRecognizer alloc] initWithTarget:self
action:@selector(tapGesture:)];
[singleTap setNumberOfTapsRequired:1];
[singleTap setNumberOfTouchesRequired:touch];
[singleTap requireGestureRecognizerToFail:doubleTap];
[actorsView addGestureRecognizer:tripleTap];
[actorsView addGestureRecognizer:doubleTap];
[actorsView addGestureRecognizer:singleTap];
}
return YES;
}
return NO;
}
In Listing 8-9, we see the task doSetup for the class TapGestureController . In this task,
we generate the 12 Powerup objects and add them as actors. We also keep track of each
Powerup in the NSMutableArray powerups . After creating the Powerup objects, we create
12 UITapGestureRecognizers —done for each Powerup . Each UITapGestureRecognizer is
added to actorsView with the task addGestureRecognizer :. Note that we are creating a
UITapGestureRecognizer for each possible combination of taps and touches, instead of trying to
use a single UITapGestureRecognizer to recognize the various combinations. Although it is possible
in some cases to do this, everything works a lot better when you are as concise as possible with
UIGestureRecognizers , as there are some subtle interactions between gesture recognizers. For
example, the recognizer responsible for detecting triple taps has to cancel those responsible for
double and single taps.
Each UITapGestureRecognizer is configured to call tapGesture : when a gesture is recognized, as
shown in Listing 8-10.
Listing 8-10. TapGestureController.m (tapGesture:)
- (void)tapGesture:(UITapGestureRecognizer *)sender{
int taps=[sender numberOfTapsRequired];
int touches=[sender numberOfTouches];
int index=(taps-1)*4+(touches-1);