UIPageViewController scroll automatically issue

Question

I have implemented automatic scrolling of UIPageViewController after every 5 seconds using timer like this:

     _bannerTimer = [NSTimer scheduledTimerWithTimeInterval:5.0
                                         target:self
                                       selector:@selector(loadNextController)
                                       userInfo:nil
                                        repeats:YES];


  - (void)loadNextController
        {

        self.index++;

        HeaderAdVC *nextViewController;
        if(self.index>arrayImages.count-1)
        {
            self.index=0;
            [pageIndicator setCurrentPage:0];
            nextViewController = [self viewControllerAtIndex:0];
        }
        else
        {
            nextViewController = [self viewControllerAtIndex:self.index];
        }


        [pageIndicator setCurrentPage:self.index];
        [pageController setViewControllers:@[nextViewController]
                                 direction:UIPageViewControllerNavigationDirectionForward
                                  animated:YES
                                completion:nil];


    }

and removing the timer in viewWillDisappear

-(void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];

    [_bannerTimer invalidate];
}

Problem :

My problem is when the loadNextController method is called my app stop responding. If i switch to next page still getting the same problem on every view.

I don't have any error in console. My all UI are just stop responding for a bit of time. — Arpit Javerya, Jun 29 '17 at 09:30
check my ans [here](https://stackoverflow.com/questions/26668536/uipageviewcontroller-automatic-scrolling-in-ios/34505406#34505406). It was working fine for me. — luckyShubhra, Jun 29 '17 at 09:32

score 1 · Accepted Answer · answered Jun 29 '17 at 10:33

Do some changes like below , do all non-ui task in background thread and all UI operation in Main thread ,try this

- (void)loadNextController
{

    dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){

        self.index++;

        HeaderAdVC *nextViewController;
        if(self.index>arrayImages.count-1)
        {
            self.index=0;
            [pageIndicator setCurrentPage:0];
            nextViewController = [self viewControllerAtIndex:0];
        }
        else
        {
            nextViewController = [self viewControllerAtIndex:self.index];
        }

        dispatch_async(dispatch_get_main_queue(), ^{
            [pageIndicator setCurrentPage:self.index];
            [pageController setViewControllers:@[nextViewController]
                                     direction:UIPageViewControllerNavigationDirectionForward
                                      animated:YES
                                    completion:nil];
        });



    });
}

i hope this will help you ..

UIPageViewController scroll automatically issue

1 Answers1