Loop UIScrollView with PageController - ios

Question

I've found a good solution for looping my scrollview, but I'm also using a UIPageControl for showing what the actual page's number is.
I change the pageControl.currentPage property when the scrollview scrolls, so if you scroll the scrollview more than a half the pageControl shows the new page.
I'd like to keep this feature, but with my actual code the pageNumber is not correct.
I think I should use this: https://github.com/gblancogarcia/GBInfiniteScrollView
But I can't make it work...
Here's my code:
-(void)rotateIfNecessary{
if(scrollView.contentOffset.x == 0) {
CGPoint newOffset = CGPointMake(scrollView.bounds.size.width+scrollView.contentOffset.x, scrollView.contentOffset.y);
[scrollView setContentOffset:newOffset];
[self rotateViewsRight];
}
else if(scrollView.contentOffset.x == (scrollView.contentSize.width - scrollView.frame.size.width) ) {
CGPoint newOffset = CGPointMake(scrollView.contentOffset.x-scrollView.bounds.size.width, scrollView.contentOffset.y);
[scrollView setContentOffset:newOffset];
[self rotateViewsLeft];
}
}
-(void)rotateViewsRight {
NSMutableArray* controllers = [DashboardFrameUtil getFrameViewControllers];
DashboardFrameViewController *endView = [controllers lastObject];
[controllers removeLastObject];
[controllers insertObject:endView atIndex:0];
[self resizePages];
}
-(void)rotateViewsLeft {
NSMutableArray* controllers = [DashboardFrameUtil getFrameViewControllers];
DashboardFrameViewController *endView = [controllers firstObject];
[controllers removeObjectAtIndex:0];
[controllers addObject:endView];
[self resizePages];
}
Then I call rotateIfNecessary in my scrollViewDidEndDecelerating, everything works fine, but the page calculating.. (when the scrollview resizes itself, it calls the scrollViewDidScroll where I calculate the pageNumber:
CGFloat pageWidth = scrollView.frame.size.width;
int page = floor((scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
pageControl.currentPage = page;
The pageControl doesn't show the correct page number when the scrollView loops.
Any idea?
Thank you in advance!

Answer 1

Let's start with:
if(scrollView.contentOffset.x == 0) {
CGPoint newOffset = CGPointMake(scrollView.bounds.size.width+scrollView.contentOffset.x, scrollView.contentOffset.y);
...
}
condition is true when scrollView.contentOffset.x == 0, so what for do you add scrollView.contentOffset.x (it's surely = 0) to scrollView.bounds.size.width ?
UPDATED
I didn't run code - there can be some mistakes
If I understand correctly when you, for example, rotate right - last element became first and you want LAST page to be showen?
If yes -- the problem with pages is because you change contentOffset all the time and also change 'data source' of scroll view, so there's no correlation between contentOffset and individual DashboardFrameViewController - same DashboardFrameViewController can be at different offsets in different moments of time. So You have to calculate page N according to something else.
For example:
Somewhere in ivar store initial controllers (with initial order):
- (void)viewDidLoad {
[super viewDidLoad];
_initialControllers = [[DashboardFrameUtil getFrameViewControllers] copy];
}
then you need some method to discover what vc is currently vissible or nearest to center (and store in ivar _currentlyVissibleVC), for example:
- (DashboardFrameViewController *)vissibleVC {
for (DashboardFrameViewController *vc in _initialControllers){
if (CGRectContainsPoint(vc.frame, CGPointMake(scrollView.contentOffset.x + scrollView.bounds.size.width/2, scrollView.contentOffset)){
_currentlyVissibleVC = vc;
return;
}
}
}
then you can calculate page num:
int pageN = [_initialControllers indexOfObject:_currentlyVissibleVC] + 1;
Hope helps