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私は現在、ストーリーボードに3つのUIViewControllerを持っていて、それらをscrollViewで1つのUIPageViewControllerに接続しました。しかし、私はいくつかの問題は、ページビューコントロールのすべてのUIViewControllerをプリロードしていないため、UIViewControllerの中心にアプリケーションを初期化しています。私はscrollview contentOffsetを使用して、ユーザーが最初にアプリケーションを開いたときに中央のViewControllerを表示しますviewDidLoad。UIPageViewController（Swift）にすべてのUIViewControllerをあらかじめロード
：
var currentIndex = 0
var mainScrollView = UIScrollView()
lazy var ViewControllerArray: [UIViewController] = {
return [self.ViewControllerInstance(name: "RightVC"),
self.ViewControllerInstance(name: "CenterVC"),
self.ViewControllerInstance(name: "LeftVC")]
}()
private func ViewControllerInstance(name: String) -> UIViewController{
return UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: name)
}
override func viewDidLoad() {
super.viewDidLoad()
self.dataSource = self
self.delegate = self
if let CenterViewController = ViewControllerArray.first {
setViewControllers([CenterViewController] , direction: .reverse, animated: false, completion: nil)
}
}
override func viewDidAppear(_ animated: Bool) {
mainScrollView = view.subviews.filter { $0 is UIScrollView }.first as! UIScrollView
mainScrollView.delegate = self
mainScrollView.contentOffset.x = self.view.bounds.size.width * 2
}
public func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
guard let ViewControllerIndex = ViewControllerArray.index(of: viewController) else {
return nil
}
let PreviousIndex = ViewControllerIndex - 1
currentIndex = ViewControllerIndex
guard PreviousIndex >= 0 else {
return nil
}
guard ViewControllerArray.count > PreviousIndex else {
return nil
}
return ViewControllerArray[PreviousIndex]
}
public func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
guard let ViewControllerIndex = ViewControllerArray.index(of: viewController) else {
return nil
}
let NextIndex = ViewControllerIndex + 1
currentIndex = ViewControllerIndex
guard NextIndex < ViewControllerArray.count else {
return nil
}
guard ViewControllerArray.count > NextIndex else {
return nil
}
return ViewControllerArray[NextIndex]
}
// Control bounce @ DidScroll & EndDragging
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let lastPosition = scrollView.contentOffset.x
if (currentIndex == ViewControllerArray.count - 1) && (lastPosition > scrollView.frame.width) {
scrollView.contentOffset = CGPoint(x: scrollView.bounds.size.width, y: 0)
} else if currentIndex == 0 && lastPosition < scrollView.frame.width {
scrollView.contentOffset = CGPoint(x: scrollView.bounds.size.width, y: 0)
}
}
// ^^
func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
let lastPosition = scrollView.contentOffset.x
if (currentIndex == ViewControllerArray.count - 1) && (lastPosition > scrollView.frame.width) {
scrollView.contentOffset = CGPoint(x: scrollView.bounds.size.width, y: 0)
} else if currentIndex == 0 && lastPosition < scrollView.frame.width {
scrollView.contentOffset = CGPoint(x: scrollView.bounds.size.width, y: 0)
}
}