UIPageViewController Gesture recognizers

I have a UIPageViewController load with my Viewcontroller.

The view controllers have buttons which are overridden by the PageViewControllers gesture recognizers.

For example I have a button on the right side of the viewcontroller and when you press the button, the PageViewController takes over and changes the page.

How can I make the button receive the touch and cancel the gesture recognizer in the PageViewController?

I think the PageViewController makes my ViewController a subview of its view.

I know I could turn off all of the Gestures, but this isn't the effect I'm looking for.

I would prefer not to subclass the PageViewController as apple says this class is not meant to be subclassed.

Solution 1:

Here is another solution, which can be added in the viewDidLoad template right after the self.view.gestureRecognizers = self.pageViewController.gestureRecognizers part from the Xcode template. It avoids messing with the guts of the gesture recognizers or dealing with its delegates. It just removes the tap gesture recognizer from the views, leaving only the swipe recognizer.

self.view.gestureRecognizers = self.pageViewController.gestureRecognizers;

// Find the tap gesture recognizer so we can remove it!
UIGestureRecognizer* tapRecognizer = nil;    
for (UIGestureRecognizer* recognizer in self.pageViewController.gestureRecognizers) {
    if ( [recognizer isKindOfClass:[UITapGestureRecognizer class]] ) {
        tapRecognizer = recognizer;
        break;
    }
}

if ( tapRecognizer ) {
    [self.view removeGestureRecognizer:tapRecognizer];
    [self.pageViewController.view removeGestureRecognizer:tapRecognizer];
}

Now to switch between pages, you have to swipe. Taps now only work on your controls on top of the page view (which is what I was after).

Solution 2:

You can override

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

to better control when the PageViewController should receive the touch and not. Look at "Preventing Gesture Recognizers from Analyzing Touches" in Dev API Gesture Recognizers

My solution looks like this in the RootViewController for the UIPageViewController:

In viewDidLoad:

//EDITED Need to take care of all gestureRecogizers. Got a bug when only setting the delegate for Tap
for (UIGestureRecognizer *gR in self.view.gestureRecognizers) {
    gR.delegate = self;
}

The override:

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
    //Touch gestures below top bar should not make the page turn.
    //EDITED Check for only Tap here instead.
    if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]) {
        CGPoint touchPoint = [touch locationInView:self.view];
        if (touchPoint.y > 40) {
            return NO;
        }
        else if (touchPoint.x > 50 && touchPoint.x < 430) {//Let the buttons in the middle of the top bar receive the touch
            return NO;
        }
    }
    return YES;
}

And don't forget to set the RootViewController as UIGestureRecognizerDelegate.

(FYI, I'm only in Landscape mode.)

EDIT - The above code translated into Swift 2:

In viewDidLoad:

for gr in self.view.gestureRecognizers! {
    gr.delegate = self
}

Make the page view controller inherit UIGestureRecognizerDelegate then add:

func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldReceiveTouch touch: UITouch) -> Bool {
    if let _ = gestureRecognizer as? UITapGestureRecognizer {
        let touchPoint = touch .locationInView(self.view)
        if (touchPoint.y > 40 ){
            return false
        }else{
            return true
        }
    }
    return true
}