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我按照Ray Wenderlich教程創建了分頁ScrollView。不過，我似乎遇到了一些問題...我的ScrollView中只加載2頁
當我運行應用程序時，只有2個圖像（頁面）似乎加載。然後，即使我可以通過它們「滾動」，接下來的3也不會出現。我試圖刪除一個清除功能，將刪除不需要的照片，因爲它是「懶惰」加載。
另外，我的pageControl也不起作用。儘管我已經用調試器進行了測試，並且該變量確實存在。
class PagedScrollViewController: UIViewController, UIScrollViewDelegate {
@IBOutlet var scrollView: UIScrollView!
@IBOutlet var pageControl: UIPageControl!
var pageImages: [UIImage] = []
var pageViews: [UIImageView?] = []
override func viewDidLoad() {
super.viewDidLoad()
// 1
pageImages = [UIImage(named: "photo1.png")!,
UIImage(named: "photo2.png")!,
UIImage(named: "photo3.png")!,
UIImage(named: "photo4.png")!,
UIImage(named: "photo5.png")!]
let pageCount = pageImages.count
// 2
pageControl.currentPage = 4
pageControl.numberOfPages = pageCount
// 3
for _ in 0..<pageCount {
pageViews.append(nil)
}
// 4
let pagesScrollViewSize = scrollView.frame.size
scrollView.contentSize = CGSize(width: pagesScrollViewSize.width * CGFloat(pageImages.count),
height: pagesScrollViewSize.height)
// 5
loadVisiblePages()
}
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 = 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 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)))
// Update the page control
pageControl.currentPage = page
// Work out which pages you want to load
let firstPage = page - 1
let lastPage = page + 1
// Load pages in our range
for index in firstPage...lastPage {
loadPage(index)
}
}
func scrollViewDidScroll(scrollView: UIScrollView) {
// Load the pages that are now on screen
loadVisiblePages()
}
}