Question

I’m trying to implement a page-scroll functionality in my project. I develop for iOS 5, with storyboards (and ARC). This is what I did in my storyboard :

The first viewController (on the left) has a scrollView and a pageControl. Its class is called GlobalDashboardViewController, and inherits from the class DashboardViewController (which inherits from UIViewController). The other 2 controllers are simple UIViewControllers with identifiers (MainDashboard and SecondaryDashboard).

In GlobalDashboardViewController.m, there is only a viewDidLoad, which gets the childViewControllers :

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"MainDashboard"]];
    [self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"SecondaryDashboard"]];
}

DashboardViewController.m is a bit more complex. Here are the most important methods :

- (void)viewDidLoad
{
    // Calling the viewDidLoad above to populate the childViewControllers array
    [super viewDidLoad];

    [self.scrollView setPagingEnabled:YES];
    [self.scrollView setScrollEnabled:YES];
    [self.scrollView setShowsHorizontalScrollIndicator:NO];
    [self.scrollView setShowsVerticalScrollIndicator:NO];
    [self.scrollView setDelegate:self];
}


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

    self.pageControl.currentPage = 0;
    _page = 0;
    [self.pageControl setNumberOfPages:[self.childViewControllers count]];

    UIViewController *viewController = [self.childViewControllers objectAtIndex:self.pageControl.currentPage];
    if (viewController.view.superview != nil) {
        [viewController viewWillAppear:animated];
    }

    self.scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * [self.childViewControllers count], scrollView.frame.size.height);
}

There are plenty of other methods, but I don’t think they’re relevant, because here is my problem: the app launches, and I see the scrollView and the pageControl. The background is dark gray, as I set it in the GlobalDashboard viewController. I can scroll correctly, and the pageControl is updated. But I don’t see the other views. When I place a breakpoint at the if in viewWillAppear, and look at viewController, it’s named correctly (Dashboard Page 1, which is the name I gave to the controller in the storyboard), but its _view property shows 0x00000000, as you can see here :

So, I never get inside the if, which is where some of the magic of actually showing the viewControllers happens…

My work is based on an example project you can find here : PageViewController. When I run it, it works perfectly. I have no clue why I can’t make it work in my own project.

Any ideas ?

Thanks

Answer 1

You never add the view itself ([self.view addSubview:/*Your child controller's view*/]). The project you linked to does it in - (void)loadScrollViewWithPage:(int)page inside PagerViewController.m