在平移視圖中實時檢測scrollView位置

Question

最初啟動時，我有一個平移的UIViewController，它加載了兩個單獨的XIB視圖，用戶可以滑動這些視圖來遍歷。 一旦用戶在總寬度（兩個視圖的平移寬度）上滑動2/3，我想觸發代碼，但是我的檢測無效。

到目前為止，這是我的代碼...

let vc0 = ViewController0(nibName: "ViewController0", bundle: nil)
let vc1 = ViewController1(nibName: "ViewController1", bundle: nil)

class ViewController: UIViewController {

    @IBOutlet weak var scrollView: UIScrollView!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.addChildViewController(vc0)
        self.scrollView.addSubview(vc0.view)
        vc0.didMoveToParentViewController(self)

        var frame1 = vc1.view.frame
        frame1.origin.x = self.view.frame.size.width
        vc1.view.frame = frame1


        self.addChildViewController(vc1)
        self.scrollView.addSubview(vc1.view)
        vc1.didMoveToParentViewController(self)

        self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width * 2, self.view.frame.size.height - 66)

        // This doesn't work
        scrollView.delegate = self


        // If the user user swipes 2/3 in (or it can be any other offset that's practical)
        if (scrollView.contentOffset.x > (self.view.frame.size.width*2)*(2/3)) {
             // Code I'd like to execute
             // ...
        }
 }

Swift怎么可能？

Answer 1

您應該使用以下方式設置滾動視圖的委托

scrollView.delegate = self

並聲明您的類實現了UIScrollViewDelegate ：

class ViewController: UIViewController, UIScrollViewDelegate

然后實現scrollViewDidScroll ，每次滾動視圖的滾動更改時都會調用它。

func scrollViewDidScroll(scrollView: UIScrollView) {
   // If the user user swipes 2/3 in (or it can be any other offset that's practical)
   if (scrollView.contentOffset.x > (self.view.frame.size.width*2)/(2/3)) {
     // Code I'd like to execute
     // ...
   }
}