Strange behavior of Page View Controller on iPhone 6 and iPhone 6 Plus

Question

I trying to implement page view controller with three pages. I already did it, it works very well on iPhones with 3.5- and 4-inch displays, but something wrong happens with 4.7- and 5.5-inch displays.

I found that hiding of standard Page Control of UIPageViewController is reason of this bug: when page control gets hidden the view of UIPageVC changes his height (+ height of Page Control View).

My page content view controllers has constraints for background image view to fit to all sizes.

This is first page:

This is second page:

This is third page, ok, we've reached last page:

But look what happens when we return to the second page (View of page content controller fully moved at few pixels to the left):

Swipe to the first page - the same result:

BUT! Look what we have when after the first page we go to the second page! Now view of page content controller at the right position by x:

Go to the last page:

Let's come back to the second page! Holy ****! View gets moved by something again:

Go to the first page, all in the 'right' (BAD) positions:

Go back to the second page from first page. All in the good and right positions:

So, my question is what is going on with this UIPageViewController? I thought that my constraints gets broken but I have nothing in my logs about it, in storyboard there are no error related to constraints.

When I use two methods "presentationCountForPageViewController:, presentationIndexForPageViewController:" all is good but above the button appears a white line of height equal to Page Control view's height (so, I need to hide it by erasing two methods listed above).

Thanks in advance for you future suggestions!

Answer 1

I fixed it! But not by the right way because it is iOS-side bug.

So, when you trying to hide Page Control View of your UIPageViewController the private 'pageSpacing' property gets broken on iPhone 6 and iPhone 6 Plus by unexpected reason. It is hard to see and understand it from views. In my case for iPhone 6 InterPageSpacing property has been decreased by 4 and for iPhone 6 Plus - by 6 values. So, if you'll try to to set pageSpacing property for iPhone 4 or 5 you'll see a white line between pages but on 6 and 6 Plus this line disappears and view of second controller moves to few pixels left.

For now I just set different values for UIPageViewControllerOptionInterPageSpacingKey while initialize my UIPageViewController:

- (id)initWithTransitionStyle:(UIPageViewControllerTransitionStyle)style navigationOrientation:(UIPageViewControllerNavigationOrientation)navigationOrientation options:(NSDictionary *)options
{
    NSMutableDictionary *dictionary = [NSMutableDictionary new];
    NSNumber *pageSpacing =
    IS_IPHONE_4_OR_LESS
    ? @(0)
    : IS_IPHONE_5
    ? @(0)
    : IS_IPHONE_6
    ? @(4)
    : @(6);

    [dictionary setValue:pageSpacing forKey:UIPageViewControllerOptionInterPageSpacingKey];

    self = [super initWithTransitionStyle:style navigationOrientation:navigationOrientation options:dictionary];
    return self;
}

Yes, fix is dirty but I didn't find another way to fix it, especially as it is bug of Apple.