UIGestureRecognizer movements restrictions

I want to know if there is a way to restrict the size or movements of the UIViews in the GestureRecognizers.

Sure I c开发者_如何学Pythonould write my own restriction code but wana know if we can set some property or something to have some bound limits.

For example in UIPanGestureRecognizer I want to restrict the movement of the view added to PanGesture within a particular CGRect, so is there any way I can set that bounding rect so on sensing PanGesture if the view is going out of my bounding frame it wont allow it.

as far as I am aware you have to write that yourself.

tap gestures let you set how many taps you are responding to with how many fingers, but most of them do not provide a lot of helpers.

I think the simplest way to accomplish this is to create an invisible view in that rect and add the gesture to it. Example: You want to detect the movement in view X inside the rect {a,b,c,d}. Create a UIView Y in the {a,b,c,d} rect. Set it's background color to clearColor. Create the gesture recognizer and add it to the Y view. In the gesture's selector do something like this:

- (void) selector:(UIPanGestureRecognizer *) gesture
{
    UIView *viewX = [self.view viewWithTag:kTagViewX];
    //now you know that the gesture took place and you have access to your view
}

If you need to change the rect in which you want the gesture to be active , just move the Y view and voila!

EDIT:

You can also use the UIGestureRecognizer delegate and return TRUE or FALSE in this method:

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;

depending on the position of that touch argument. Actually this is the way Apple suggest's in one of their WWDC session videos. And it's better since you don't have to add another view and fill up the memory.