ScrollView和菜單項下的小橫條？

Question

我在我的菜單項下有一個單槓視圖，每當我點擊其中一個菜單項時，它就會出現在該項下。我在代碼中將其命名爲movingView。下面是截圖：

這菜單下我有一個UIScrollView。我在UIScrollView內部放置了5個視圖，我可以在它們之間滑動。現在，每當我滑動，我想要我的菜單項下的單槓視圖按照我的選擇。例如，當我點擊手槍時，它從步槍移動到手槍。當我從UIScrollView內的第一頁滑動到第二頁時，我希望發生這種情況。

請別人幫我。已經3天了，我無法弄清楚如何做到這一點。

我的代碼：

class TabViewController: UIViewController 
{ 
    @IBOutlet var scrollView: UIScrollView! 
    @IBOutlet var buttons: [UIButton]! 
    @IBOutlet var backgroundView: UIImageView! 

    var movingView = UIView() 

    let screenWidth = UIScreen.main.bounds.width 

    var rifleViewController: UIViewController! 
    var pistolViewController: UIViewController! 
    var shotgunViewController: UIViewController! 
    var smgsViewController: UIViewController! 
    var sniperViewController: UIViewController! 

    override func viewDidLoad() 
    { 
     super.viewDidLoad() 

     let main = UIStoryboard(name: "Main", bundle: nil) 

     rifleViewController = main.instantiateViewController(withIdentifier: "rifles") 
     sniperViewController = main.instantiateViewController(withIdentifier: "snipers") 
     smgsViewController = main.instantiateViewController(withIdentifier: "smgss") 
     shotgunViewController = main.instantiateViewController(withIdentifier: "shotguns") 
     pistolViewController = main.instantiateViewController(withIdentifier: "pistols") 

     self.scrollView.contentSize = CGSize(width: self.view.frame.width * 5, height: self.view.frame.height) 

     rifleViewController.view.frame = scrollView.bounds 
     scrollView.addSubview(rifleViewController.view) 

     pistolViewController.view.frame = scrollView.bounds 
     pistolViewController.view.frame.origin.x = scrollView.frame.size.width 
     scrollView.addSubview(pistolViewController.view) 

     shotgunViewController.view.frame = scrollView.bounds 
     shotgunViewController.view.frame.origin.x = scrollView.frame.size.width * 2 
     scrollView.addSubview(shotgunViewController.view) 

     smgsViewController.view.frame = scrollView.bounds 
     smgsViewController.view.frame.origin.x = scrollView.frame.size.width * 3 
     scrollView.addSubview(smgsViewController.view) 

     sniperViewController.view.frame = scrollView.bounds 
     sniperViewController.view.frame.origin.x = scrollView.frame.size.width * 4 
     scrollView.addSubview(sniperViewController.view) 


     movingView = UIView(frame: CGRect(x: 0, y: backgroundView.frame.maxY - 5, width: screenWidth/5, height: 10)) 
     movingView.backgroundColor = UIColor.white 
     backgroundView.addSubview(movingView) 

    } 

    override func didReceiveMemoryWarning() 
    { 
     super.didReceiveMemoryWarning() 
    } 

    @IBAction func riflePressTab(_ sender: Any) 
    { 
     scrollView.setContentOffset(CGPoint(x: 0, y: 0) , animated: true) 
    } 

    @IBAction func pistolPressTab(_ sender: Any) 
    { 
     scrollView.setContentOffset(CGPoint(x: scrollView.frame.size.width, y: 0) , animated: true) 
    } 

    @IBAction func shotgunPressTab(_ sender: Any) 
    { 
     scrollView.setContentOffset(CGPoint(x: scrollView.frame.size.width * 2, y: 0) , animated: true) 
    } 

    @IBAction func smgsPressTab(_ sender: Any) 
    { 
     scrollView.setContentOffset(CGPoint(x: scrollView.frame.size.width * 3, y: 0) , animated: true) 
    } 

    @IBAction func sniperPressTab(_ sender: Any) 
    { 
     scrollView.setContentOffset(CGPoint(x: scrollView.frame.size.width * 4, y: 0) , animated: true) 
    } 


    @IBAction func didPressTab(_ sender: UIButton) 
     { 

     let newx = sender.frame.origin.x 

     UIView.animate(withDuration: 0.2) 
      { 
      self.movingView.frame.origin.x = newx 
      } 
     } 
} 

我已經試過這個，但是當我跑我的應用程序，沒有任何反應，當我滾動

func scrollViewDidScroll(_ scrollView: UIScrollView) { 

    //Assuming your views are of full screen width or just change the SCREEN_WIDTH to whatever width your views occupy 
    //This will give you which index you are on, i.e you are showing the first view or second or third 
    let newIndex = scrollView.contentOffset.x/UIScreen.main.bounds.size.width; 

    animateUnderBar(forIndex index:Int(newIndex)) 
} 

func animateUnderBar(forIndex index:Int){ 

    let newx = self.movingView.frame.origin.x + CGFloat(index) * self.movingView.bounds.size.width 

    UIView.animate(withDuration: 0.2) 
    { 
     self.movingView.frame.origin.x = newx 
    } 
} 

Answer 1

讓你的類符合UIScrollViewDelegate並實現以下方法 -

func scrollViewDidScroll(_ scrollView: UIScrollView) { 

    //Assuming your views are of full screen width or just change the SCREEN_WIDTH to whatever width your views occupy 
    //This will give you which index you are on, i.e you are showing the first view or second or third 
    let newIndex = scrollView.contentOffset.x/UIScreen.main.bounds.size.width; 

    animateUnderBar(forIndex :Int(newIndex)) 
} 

func animateUnderBar(forIndex index:Int){ 

    let newx = view.frame.origin.x + CGFloat(index) * view.bounds.size.width 

    UIView.animate(withDuration: 0.2) 
     { 
     self.movingView.frame.origin.x = newx 
     } 
    } 
} 

或者

您應該使用UICollectionView而不是UIScrollView，因爲它將自動處理單元格內部的視圖顯示，而無需手動設置contentOffSet。在酒吧下移動也會更容易，因爲它只是使用indexPath.item屬性移動下方酒吧的問題。