How can I recreate the iOS App Store image slideshow? - ios

Question

So I am pretty new to Swift still and I was wondering if anyone could help me recreate the image slideshow at the top of the iOS Appstore.
Is it a scrollview with UIImageViews or CollectionView cells?
I tried following and modifying this Ray Wenderlich tutorial but the result I got laisse à désirer as can be seen in the image below.
Instead of three images showing I only got two and none completely filled the scrollView which leads me to think it might be a problem with auto layout.
Would really appreciate all the help I can get.
Anyway here is my code:
var pageImages = [UIImage]()
var pageViews: [UIImageView?] = []
#IBOutlet weak var carousel: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
//Setting up the image carousel
pageImages = [UIImage(named: "featured_1")!, UIImage(named: "featured_2")!, UIImage(named: "featured_3")!]
for _ in 0..<pageImages.count {
pageViews.append(nil)
}
let pagesScrollViewSize = carousel.frame.size
carousel.contentSize = CGSize(width: pagesScrollViewSize.width * CGFloat(pageImages.count),
height: pagesScrollViewSize.height)
}
func loadPage(page: Int) {
if page < 0 || page >= pageImages.count {
// If it's outside the range of what you have to display, then do nothing
return
}
// 1
if let pageView = pageViews[page] {
// Do nothing. The view is already loaded.
} else {
// 2
var frame = carousel.bounds
frame.origin.x = frame.size.width * CGFloat(page)
frame.origin.y = 0.0
// 3
let imageView = UIImageView(image: pageImages[page])
imageView.contentMode = .ScaleAspectFit
imageView.frame = frame
carousel.addSubview(imageView)
// 4
pageViews[page] = imageView
}
}
func purgePage(page: Int) {
if page < 0 || page >= pageImages.count {
// If it's outside the range of what you have to display, then do nothing
return
}
// Remove a page from the scroll view and reset the container array
if let pageView = pageViews[page] {
pageView.removeFromSuperview()
pageViews[page] = nil
}
}
func loadVisiblePages() {
// First, determine which page is currently visible
let pageWidth = carousel.frame.size.width
let page = Int(floor((carousel.contentOffset.x * 2.0 + pageWidth) / (pageWidth * 2.0)))
// Work out which pages you want to load
let firstPage = page - 1
let lastPage = page + 1
// Purge anything before the first page
for var index = 0; index < firstPage; ++index {
purgePage(index)
}
// Load pages in our range
for index in firstPage...lastPage {
loadPage(index)
}
// Purge anything after the last page
for var index = lastPage+1; index < pageImages.count; ++index {
purgePage(index)
}
}
override func scrollViewDidScroll(scrollView: UIScrollView) {
loadVisiblePages()
}
}