UIPageViewController Gesture recognizers

Question

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.

Answer 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).

Answer 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
}

Answer 3

I had the same problem. The sample and documentation does this in loadView or viewDidLoad:

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

This replaces the gesture recognizers from the UIViewControllers views with the gestureRecognizers of the UIPageViewController. Now when a touch occurs, they are first sent through the pageViewControllers gesture recognizers - if they do not match, they are sent to the subviews.

Just uncomment that line, and everything is working as expected.

Phillip

Answer 4

Setting the gestureRecognizers delegate to a viewController as below no longer work on ios6

for (UIGestureRecognizer *gR in self.view.gestureRecognizers) {
    gR.delegate = self;
}

In ios6, setting your pageViewController's gestureRecognizers delegate to a viewController causes a crash

Answer 5

In newer versions (I am in Xcode 7.3 targeting iOS 8.1+), none of these solutions seem to work.

The accepted answer would crash with error:

UIScrollView's built-in pan gesture recognizer must have its scroll view as its delegate.

The currently highest ranking answer (from Pat McG) no longer works as well because UIPageViewController's scrollview seems to be using odd gesture recognizer sub classes that you can't check for. Therefore, the statement if ( [recognizer isKindOfClass:[UITapGestureRecognizer class]] ) never executes.

I chose to just set cancelsTouchesInView on each recognizer to false, which allows subviews of the UIPageViewController to receive touches as well.

In viewDidLoad:

guard let recognizers = self.pageViewController.view.subviews[0].gestureRecognizers else {
    print("No gesture recognizers on scrollview.")
    return
}

for recognizer in recognizers {
    recognizer.cancelsTouchesInView = false
}

Answer 6

I used

for (UIScrollView *view in _pageViewController.view.subviews) {
    if ([view isKindOfClass:[UIScrollView class]]) {
        view.delaysContentTouches = NO;
    }
}

to allow clicks to go through to buttons inside a UIPageViewController

Answer 7

In my case I wanted to disable tapping on the UIPageControl and let tapping being received by another button on the screen. Swipe still works. I have tried numerous ways and I believe that was the simplest working solution:

for (UIPageControl *view in _pageController.view.subviews) {
    if ([view isKindOfClass:[UIPageControl class]]) {
        view.enabled = NO;
    }
}

This is getting the UIPageControl view from the UIPageController subviews and disabling user interaction.

Answer 8

Just create a subview (linked to a new IBOutlet gesturesView) in your RootViewController and assign the gestures to this new view. This view cover the part of the screen you want the gesture enable.

in viewDidLoad change :

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

to :

self.gesturesView.gestureRecognizers = self.pageViewController.gestureRecognizers;

Answer 9

Also can use this (thanks for help, with say about delegate):

// add UIGestureRecognizerDelegate

NSPredicate *tp = [NSPredicate predicateWithFormat:@"self isKindOfClass: %@", [UITapGestureRecognizer class]];
UITapGestureRecognizer *tgr = (UITapGestureRecognizer *)[self.pageViewController.view.gestureRecognizers filteredArrayUsingPredicate:tp][0];
tgr.delegate = self; // tap delegating

NSPredicate *pp = [NSPredicate predicateWithFormat:@"self isKindOfClass: %@", [UIPanGestureRecognizer class]];
UIPanGestureRecognizer *pgr = (UIPanGestureRecognizer *)[self.pageViewController.view.gestureRecognizers filteredArrayUsingPredicate:pp][0];
pgr.delegate = self; // pan delegating

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch 
{
    CGPoint touchPoint = [touch locationInView:self.view];

    if (UIInterfaceOrientationIsPortrait([[UIApplication sharedApplication] statusBarOrientation]) && touchPoint.y > 915 ) {
        return NO; // if y > 915 px in portrait mode
    }

    if (UIInterfaceOrientationIsLandscape([[UIApplication sharedApplication] statusBarOrientation]) && touchPoint.y > 680 ) {
        return NO; // if y > 680 px in landscape mode
    }

    return YES;
}

Work perfectly for me :)

Answer 10

This is the solution which worked best for me I tried JRAMER answer with was fine except I would get an Error when paging beyond the bounds (page -1 or page 23 for me)

PatMCG solution did not give me enough flexibility since it cancelled all the taprecognizers, I still wanted the tap but not within my label

In my UILabel I simply overrode as follows, this cancelled tap for my label only

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
 if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]) {
     return NO;
 } else {
     return YES;
 }
}

Answer 11

I create pageviewcontrollers regularly as my user jumps, curls, and slides to various different page views. In the routine that creates a new pageviewcontroller, I use a slightly simpler version of the excellent code shown above:

UIPageViewController *npVC = [[UIPageViewController alloc]
                       initWithTransitionStyle:UIPageViewControllerTransitionStylePageCurl
                       navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal
                       options: options];
...

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

Now the taps work as I wish (with left and right taps jumping a page, and the curls work fine.

Answer 12

Swift 3 extension for removing tap recognizer:

    import UIKit

extension UIPageViewController {
    func removeTapRecognizer() {
        let gestureRecognizers = self.gestureRecognizers

        var tapGesture: UIGestureRecognizer?
        gestureRecognizers.forEach { recognizer in
            if recognizer.isKind(of: UITapGestureRecognizer.self) {
                tapGesture = recognizer
            }
        }
        if let tapGesture = tapGesture {
            self.view.removeGestureRecognizer(tapGesture)
        }
    }
}

Answer 13

I ended up here while looking for a simple, catch-all way to respond to taps on my child view controllers within a UIPageViewController. The core of my solution (Swift 4, Xcode 9) wound up being as simple as this, in my RootViewController.swift (same structure as Xcode's "Page-Based App" template):

override func viewDidLoad() {
    super.viewDidLoad()

    ...

    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(pageTapped(sender:)))
    self.pageViewController?.view.subviews[0].addGestureRecognizer(tapGesture)
}

...

@objc func pageTapped(sender: UITapGestureRecognizer) {
    print("pageTapped")
}

(I also made use of this answer to let me keep track of which page was actually tapped, ie. the current one.)

Answer 14

I worked out a working solution. Add another UIGestureRecognizer to UIPageViewController and implement delegate method provided below. In every moment that you have to resolve which gesture should be locked or passed further this method will be called. Remember to provide a reference to confictingView, which in my case it was UITableView, which also recognizes pan gesture. This view was placed inside UIPageViewController, so a pan gesture was recognized twice or just in randomly way. Now in this method, I check if pan gesture is inside both my UITableView and UIPageViewController, and I decide that UIPanGestureRecognizer is primary.

This approach doesn't override directly any of another gesture recognizers so we don't have to worry about mentioned 'NSInvalidArgumentException'.

Keep in mind that pattern actually is not approved by Apple :)

 var conflictingView:UIView?
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        if otherGestureRecognizer.view === pageViewController?.view {

            if let view = conflictingView {
                var point = otherGestureRecognizer.location(in: self.view)
                if view.frame.contains(point) {
                    print("Touch in conflicting view")
                    return false
                }
            }
            print("Touch outside conficting view")
            return true
        }
        print("Another view passed out")
        return true
    }

Answer 15

If you're using a button that you've subclassed, you could override touchesBegan, touchesMoved, and touchesEnded, invoking your own programmatic page turn as appropriate but not calling super and passing the touches up the notification chain.