Start a UIScrollView with an image of a specific index from another view
I have a CollectionView with multiple images. Clicking on one of them opens a new view - UIScrollView.
Now every time the UIScrollView starts from the first image of the array from the collectionView.
I am passing the index (imageNumber) of the image facing the UIScrollView, but I don't know how to make the first image shown one of the indices.
override func viewDidLoad() {
super.viewDidLoad()
var numberOfImagesPerALbum = data[albumNumber].count - 1
for index in 0...numberOfImagesPerALbum {
pageImages.append(UIImage(named: data[albumNumber][index]["image"]!)!)
}
var pageCount = pageImages.count
// 2
pageControl.currentPage = imageNumber
println(imageNumber)
pageControl.numberOfPages = pageCount
// 3
for _ in 0..<pageCount {
pageViews.append(nil)
}
}
override func viewDidLayoutSubviews() {
let pagesScrollViewSize = scrollView.frame.size
scrollView.contentSize = CGSizeMake(pagesScrollViewSize.width * CGFloat(pageImages.count), pagesScrollViewSize.height)
// 5
loadVisiblePages()
}
func loadPage(page: Int) {
if page < 0 || page >= pageImages.count {
// If it 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 = scrollView.bounds
frame.origin.x = frame.size.width * CGFloat(page)
frame.origin.y = 0.0
3
let newPageView = UIImageView(image: pageImages[page])
newPageView.contentMode = .ScaleAspectFit
newPageView.frame = frame
scrollView.addSubview(newPageView)
// 4
pageViews[page] = newPageView
}
}
func purgePage(page: Int) {
if page < 0 || page >= pageImages.count {
// If it 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 = scrollView.frame.size.width
let page = Int(floor((scrollView.contentOffset.x * 2.0 + pageWidth) / (pageWidth * 2.0)))
println("Page is \(page)")
imageTitleLabel.text = data[albumNumber][page]["title"]
imageDescriptionLabel.text = data[albumNumber][page]["text"]
// Update the page control
pageControl.currentPage = page
// 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 var index = firstPage; index <= lastPage; ++index {
loadPage(index)
}
// Purge anything after the last page
for var index = lastPage+1; index < pageImages.count; ++index {
purgePage(index)
}
}
func scrollViewDidScroll(scrollView: UIScrollView) {
// Load the pages that are now on screen
loadVisiblePages()
}
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Consider UICollectionView
with UICollectionViewFlowLayout (set scrollDirection
to UICollectionViewScrollDirectionHorizontal
) instead UIScrollView
. Also set the property to a UICollectionView
pagingEnabled
value true
.
This saves you unnecessary code and you get a UICollectionView
- scrollToItemAtIndexPath:atScrollPosition:animated:
"free" method . This should solve all your problems and make your code cleaner. Good luck!
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