Add UIPageControl to UIScrollView

ios, objective-c, uipagecontrol, uiscrollview

Solution

You don't want to add the `UIPageControl` to the scroll view itself because you don't want it to scroll with the content.

With that said, take a look at the `UIScrollViewDelegate` protocol, specifically `scrollViewDidEndDecelerating:` which will be called when your scroll view stops moving (a good time to update your `UIPageControl`).

Your calculation is going to be something like..

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
   self.pageControl.currentPage = floorf(scrollView.contentOffSet.x/320);
}

Re: I have two scroll views within one view controller, so does this specify which one I'm using?

The `scrollView` instance passed in can be used to negotiate which scroll view did end decelerating. If you set the `delegate` property for both of your scroll views this will get called when either of those end decelerating so you'll need to verify which instance ended decelerating.

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
   if (scrollView == self.helpScrollView) {
       self.pageControl.currentPage = floorf(scrollView.contentOffset.x/scrollView.frame.size.width);
   }
}

Problem

I have a UIScrollView containing 5 images. I want to add a UIPageControl at the bottom of my scroll view so that the user can see what page they are on. Here is my code for the scroll view: ``` self.helpScrollView.contentSize = CGSizeMake(320 * 5, 436); UIImageView *image1 = [[UIImageView alloc] initWithFrame:CGRectMake(320 * 0, 0, 320, 436)]; image1.image = [UIImage imageNamed:[NSString stringWithFormat: @"Guide Page One.png"]]; [self.helpScrollView addSubview:image1]; UIImageView *image2 = [[UIImageView alloc] initWithFrame:CGRectMake(320 * 1, 0, 320, 436)]; image2.image = [UIImage imageNamed:[NSString stringWithFormat: @"Guide Page Two.png"]]; [self.helpScrollView addSubview:image2]; UIImageView *image3 = [[UIImageView alloc] initWithFrame:CGRectMake(320 * 2, 0, 320, 436)]; image3.image = [UIImage imageNamed:[NSString stringWithFormat: @"Guide Page Three.png"]]; [self.helpScrollView addSubview:image3]; UIImageView *image4 = [[UIImageView alloc] initWithFrame:CGRectMake(320 * 3, 0, 320, 436)]; image4.image = [UIImage imageNamed:[NSString stringWithFormat: @"Guide Page Four.png"]]; [self.helpScrollView addSubview:image4]; UIImageView *image5 = [[UIImageView alloc] initWithFrame:CGRectMake(320 * 4, 0, 320, 436)]; image5.image = [UIImage imageNamed:[NSString stringWithFormat: @"Guide Page Five.png"]]; [self.helpScrollView addSubview:image5]; self.helpScrollView.pagingEnabled = true; self.helpScrollView.showsHorizontalScrollIndicator = NO; ``` I have dragged a UIPageControl onto my scrollview in my xib file, but I don't know how to link them. How do I do this?

Original source