viewWillAppear causes controller to initialize again

[D-32]

The setup code inside viewWillAppear should only be performed once. Inside my app it happens that I push a view controller and when navigating back viewWillAppear is called again. This then causes all the pages to be setup again and the current index is reset.

[nazywamsiepawel]

hey there,

I have been facing the same issue and came up with a solution of quality proportional to the amount of time I had to investigate the issue. tl;dr - lame but works.

You need to change that :

-(void)viewWillAppear:(BOOL)animated {
    [self setupPageViewController];
    [self setupSegmentButtons];

    CGRect sizeRect = [UIScreen mainScreen].applicationFrame;
    float width = sizeRect.size.width;
    NSInteger xCoor = (width/[viewControllerArray count])*self.currentPageIndex-X_OFFSET;
    selectionBar.frame = CGRectMake(xCoor, selectionBar.frame.origin.y, selectionBar.frame.size.width, selectionBar.frame.size.height);
}

And then update the first view controller that is being loaded currentPageIndex.

-(void)setupPageViewController {
    pageController = (UIPageViewController*)self.topViewController;
    pageController.delegate = self;
    pageController.dataSource = self;
    [pageController setViewControllers:@[[viewControllerArray objectAtIndex:self.currentPageIndex]] direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:nil];
    [self syncScrollView];
}

Not sure if it was a bug or by design but in my case pushing anything on top of the navigation and then going back was causing some rather unintuitive behaviour.