Is there way to get all the pre-loaded view controllers in UIPageViewController

Question

I have an UIPageViewController. I can flip the pages and everything works fine. The UIPageViewController pre-loads one ViewController. At this point, there are two view controllers in memory (one is the visible controller while another is the pre-loaded controller). I want to get the two ViewControllers so that I could change some settings on the fly.

The question is how could I get the pre-loaded child view controllers? If I cannot get those controllers, what is the best way to reset some properties on all the preloaded view controllers?

Answer 1

You can modify your custom object which can be used to build your view controller:

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
    NSUInteger index = [(PageChildViewController *) viewController index];
    if (index == 0) {
        return nil;
    }
    index--;
    return [self viewControllerAtIndex:index];
}

- (UIViewController *)viewControllerAtIndex:(NSUInteger)index {
    CustomObject *customObject = self.customObjects[index];
    PageChildViewController *childViewController = [PageChildViewController controllerWithIndex:index andCustomObject:customObject];
    return childViewController;
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
    NSUInteger index = [(PageChildViewController *) viewController index];
    index++;
    if (index == self.pages.count) {
        return nil;
    }
    return [self viewControllerAtIndex:index];
}

If you need to update currently visible page view controller you can use this:

[self.pageController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];

If you need to reset you page view controller cache you can use this:

self.pageController.dataSource = nil;
self.pageController.dataSource = self;