Question

I’m working on a game in which an attribute of a game object is set by long pressing on the object itself. The value of the attribute is determined by the duration of the long press gesture. I’m using UILongPressGestureRecognizer for this purpose, so it’s something like this:

[gameObjectView addGestureRecognizer:[[UILongPressGestureRecognizer alloc] 
                                       initWithTarget:self action:@selector(handle:)]];

Then the handler function

- (void)handle:(UILongPressGestureRecognizer)gesture {
  if (gesture.state == UIGestureRecognizerStateEnded) {
    // Get the duration of the gesture and calculate the value for the attribute
  }
}

How do I get the duration of the long press gesture in this case?

Answer 1

I’m pretty sure the gesture doesn’t store this information for you to access. You can only set a property on it called minimumPressDuration that is the amount of time before the gesture is recognised.

Workaround with ios 5 (untested):

Create an NSTimer property called timer: @property (nonatomic, strong) NSTimer *timer;

And a counter: @property (nonatomic, strong) int counter;

Then @synthesize

- (void)incrementCounter {
    self.counter++;
}

- (void)handle:(UILongPressGestureRecognizer)gesture {
    if (gesture.state == UIGestureRecognizerStateBegan) {
         self.counter = 0;
         self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(incrementCounter) userInfo:nil repeats:yes];
    }
    if (gesture.state == UIGestureRecognizerStateEnded) {
        [self.timer invalidate];
    }
}

So when the gesture begins start a timer that fires the incrementation method every second until the gesture ends. In this case you’ll want to set the minimumPressDuration to 0 otherwise the gesture won’t start straight away. Then do whatever you want with counter!