Pagenumber in UIPageViewController

Question

I've been following This thread to get a counter for my UIPageViewController.

It works like a charm except for when i get to the first or last page, then the pagenumber stays at the page before. Fortunately the contents changes atleast.

Here's some code:

if(pageController.viewControllers.count != 0){
    ViewPostController *vpc = [pageController.viewControllers objectAtIndex:0];
    NSUInteger retreivedIndex = [self indexOfViewController:vpc];
    self.title = [NSString stringWithFormat:@"%d of %d", retreivedIndex+1, [pageImageContent count]];
}

And

- (NSUInteger)indexOfViewController:(ViewPostController *)viewController
{
NSLog(@"indexex %d", [pageNumberArray indexOfObject:viewController.pageNumber]);
return [pageNumberArray indexOfObject:viewController.pageNumber];
}

Does anyone know why the counter wont "reach" the outer numbers?

Thanks in advance

score 0 · Answer 1 · edited May 23 '17 at 12:10

This is an old question and my answer may not even directly address the issue beguiling Tom, but maybe the info will help someone. The UIPageViewController vexed me for a number of days. My mistake was to assume these methods only get called when a page is turned:

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController

In reality they seem to get called mutiple times during a page turn. I had a currentPage variable in the master viewcontroller which I incremented/decremented whenever these two methods were called, but it created bizarre behavior similar to what Tom described. I still use those methods (you have to), but do the increment/decrement in a different method. Here's what those methods look like:

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    if (self.currentPage==0) {
        return nil;
    }
    else {
        return [[self pageArray] objectAtIndex:self.currentPage-1];
    }
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
    if (self.currentPage==self.pageArray.count-1)
    {
        return nil;
    }
    else
    {
        return [[self pageArray] objectAtIndex:self.currentPage+1];
    }
}

The increment/decrement of currentPage occurs in this method:

- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
    if (completed)
    {
        int currentIndex = ((UIViewController *)[self.pageViewController.viewControllers objectAtIndex:0]).view.tag;
        self.currentPage = currentIndex;
    }
}

To use this method, you have to add both protocols

<UIPageViewControllerDataSource, UIPageViewControllerDelegate>

not just the data source, and set the delegate to self

self.pageViewController.delegate=self;

or the method won't be called. I'm using view tags to determine each page's index, but there are other ways to get this number. See this article for a discussion of ways to get the current page's index:

UIPageViewController: return the current visible view

The UIPageViewController tutorials I found on the web all showed the use of a single viewcontroller that gets reused for each page, which didn't help me because I have a separate viewcontroller for each page.

Pagenumber in UIPageViewController

1 Answers1