PageBoyViewController freeze when push a new VC during auto-scrolling transition

[nsmag]

If push a VC when the auto-scroll transition start, when back to the PageBoyVC, it will not respond to scroll/tap and autoScroller stop working too.

This is only happen with autoScroller. It's working fine with user-scroll

[corbinhudson]

I have the same issue except I am not using auto scroll (direct). I load a 3 paged table view, and when the user clicks on tab if it is empty (for first time) it pushes to new VC. When user hits back the view is frozen and will not respond

[nsmag]

I'm not sure if this happen because the completion block of scrollToPage is not called when pushing a new VC during animation

...
                self.isScrollingAnimated = animated
                let direction = directionForPageScroll(to: page, index: rawIndex)
                
                let transitionCompletion: TransitionOperation.Completion = { (finished) in
                    if finished {
                        let isVertical = self.navigationOrientation == .vertical
                        let currentPosition = CGPoint(x: isVertical ? 0.0 : CGFloat(rawIndex),
                                                      y: isVertical ? CGFloat(rawIndex) : 0.0)
                        self.currentPosition = currentPosition
                        self.currentIndex = rawIndex
                        
                        // if not animated call position delegate update manually
                        if !animated {
                            self.delegate?.pageboyViewController(self,
                                                                 didScrollTo: currentPosition,
                                                                 direction: direction,
                                                                 animated: animated)
                        }
                    }
                    
                    self.autoScroller.didFinishScrollIfEnabled()
                    completion?(viewController, animated, finished)
                    self.isScrollingAnimated = false
                }
...

setting self.isScrollingAnimated to true will disable user interaction

[corbinhudson]

I am using Tabman in combination with Pageboy, I made no changes to my code except update pod and the error occurred. Reverted Pagepoy to 2.3 & Tabamn to 1.5.2 and now is working no problem. Will wait for fix

[msaps]

@corbinhudson @nsmag okay will check it out! Looks like it was probably a regression with updating the transition stuff in 2.4

[msaps]

@nsmag @corbinhudson could you try 2.5.3 and see if that fixes the issues you're having?

I managed to reproduce issues when pushing a new VC during an animated transition - which are now fixed as seen below:

[nsmag]

@msaps looks like the issue still exists with 2.5.3.

I created a demo here

In the demo, the first VC is a Pageboy with 3 VCs (red, yellow, green)
then I use dispatch queue to push a new VC when pageboy starting transition, press back and the pageboy VC will freeze.

[msaps]

@nsmag okay thanks for that! Will check it out 👍

[msaps]

@nsmag just released 2.5.4 which should resolve the issue! Hopefully second time is the charm. 😄

The demo project really helped!

[nsmag]

@msaps It still freeze if pushing at the right moment
let's set timer in the demo to 1.9

DispatchQueue.main.asyncAfter(deadline: .now() + 1.9) {...

I updated the demo repo.

[msaps]

@nsmag are you using 2.5.4? The demo project works fine for me with the 1.9 delay on 2.5.4.

Demo with 2.5.4

[nsmag]

@msaps Sorry I forgot to pod update. The demo works fine.

I'll test it on my project.

[nsmag]

@msaps
If the PageboyVC is in table view, it'll freeze.
I'm not sure if I did anything wrong

I updated the demo repo:
the first VC is a UITableViewController with PageBoyViewController in it.

Or is there any workaround in this case?

[corbinhudson]

I tested in my project with updates, working now thanks!

[msaps]

@nsmag An additional tweak I want to make is to pause the auto scrolling when viewWillDisappear() is received and restarting on viewDidAppear - as currently the auto scrolling will continue when offscreen.

With your implementation in the UITableViewCell however, the PageboyViewController won't receive the correct lifecycle events as it is never added as a child view controller. This is probably why this issue is reproducible as it relies on viewWillAppear and other lifecycle events. I would recommend implementing this differently (perhaps the parent VC owns the child PageboyViewControllers and provides them to the cells rather than the cell owning it?)

[nsmag]

@msaps I totally forgot about child VC. I'll try another test. thanks!

[nsmag]

@msaps
2.5.4 fixed this issue

about pageboy in table view, it's my bad, I just forgot addChildViewController()
Thanks!

[ahmedk92]

Freezes on iPhone 6s Plus iOS 12.3.1 with scrollToPage. Pageboy version: 3.3.0.

Edit: It's solved now. Here's what I thought was happening:

• I had the PageboyViewController to be of a width proportional to its superview with a non-integer factor. This resulted in pages to rest on a non-integer horizontal offset (x). As I investigated, I found Pageboy to use such logic to determine if a scroll is in action.
• Solution was just to make sure the PageboyViewController's width is integer.