Change page on UIScrollView

Question

I have a UIScrollView with 10 pages. I am able to flick between them. I also want to have 2 buttons (a back button and a next button) which when touched will go to the previous or next page. I can't seem to figure out a way to do this though. A lot of my code comes from Apple's page control sample code. Can anybody help?

Thanks

Answer 1

You just tell the buttons to scroll to the page's location:

CGRect frame = scrollView.frame;
frame.origin.x = frame.size.width * pageNumberYouWantToGoTo;
frame.origin.y = 0;
[scrollView scrollRectToVisible:frame animated:YES];

Answer 2

Here is an implementation for Swift 4:

func scrollToPage(page: Int, animated: Bool) {
    var frame: CGRect = self.scrollView.frame
    frame.origin.x = frame.size.width * CGFloat(page)
    frame.origin.y = 0
    self.scrollView.scrollRectToVisible(frame, animated: animated)
}

and is easily invoked by calling:

self.scrollToPage(1, animated: true)

Edit:

A nicer way of doing this is to support both horizontal and vertical pagination. Here is a convenient extension for that:

extension UIScrollView {

    func scrollTo(horizontalPage: Int? = 0, verticalPage: Int? = 0, animated: Bool? = true) {
        var frame: CGRect = self.frame
        frame.origin.x = frame.size.width * CGFloat(horizontalPage ?? 0)
        frame.origin.y = frame.size.width * CGFloat(verticalPage ?? 0)
        self.scrollRectToVisible(frame, animated: animated ?? true)
    }

}

This creates an extension on UIScrollView where you can scroll to any page, vertical or horisontal.

self.scrollView.scrollTo(horizontalPage: 0)
self.scrollView.scrollTo(verticalPage: 2, animated: true)
self.scrollView.scrollTo(horizontalPage: 1, verticalPage: 2, animated: true)

Answer 3

Here is a static method in swift:

static func scrollToPage(scrollView: UIScrollView, page: Int, animated: Bool) {
    var frame: CGRect = scrollView.frame
    frame.origin.x = frame.size.width * CGFloat(page);
    frame.origin.y = 0;
    scrollView.scrollRectToVisible(frame, animated: animated)
}

Answer 4

If scrollRectToVisible doesn't work try this :

let frame = scrollView.frame
    let offset:CGPoint = CGPoint(x: CGFloat(sender.currentPage) * frame.size.width, y: 0)
    self.scrollView.setContentOffset(offset, animated: true)

Answer 5

scrollRectToVisible was not working for me, so I had to animate the contentOffset. This code works in swift 3.

func scrollToPage(_ page: Int) {
    UIView.animate(withDuration: 0.3) { 
        self.scrollView.contentOffset.x = self.scrollView.frame.width * CGFloat(page)
    }
}

Answer 6

Swift Solution

func changePage(pageControl: UIPageControl) {

    let page = CGFloat(pageControl.currentPage)
    var frame = self.scrollView.frame
    frame.origin.x = frame.size.width * page
    frame.origin.y = 0
    self.scrollView.scrollRectToVisible(frame, animated: true)
}