用isHidden = true隐藏横幅广告。

Question

我目前在我的GameViewController中用下面的代码从admob中调用一个Banner广告。

class GameViewController: UIViewController {
var bannerView: GADBannerView!
}

override func viewDidLoad() {
    super.viewDidLoad()
    bannerView = GADBannerView(adSize: kGADAdSizeBanner)
    addBannerViewToView(bannerView)
    bannerView.adUnitID = "ca-app-pub-XXXXXXXXX"  // Default Google Test Ad Address
    bannerView.rootViewController = self
    bannerView.load(GADRequest())
    bannerView.isHidden = false // <----- This works, but doesn't work in GameScene.swift

这是从上面的代码（也是在GameViewController中）调用的函数来显示广告。

func addBannerViewToView(_ bannerView: GADBannerView) {
   bannerView.translatesAutoresizingMaskIntoConstraints = false
   view.addSubview(bannerView)
   view.addConstraints(
     [NSLayoutConstraint(item: bannerView,
                         attribute: .bottom,
                         relatedBy: .equal,
                         toItem: bottomLayoutGuide,
                         attribute: .top,
                         multiplier: 1,
                         constant: 0),
      NSLayoutConstraint(item: bannerView,
                         attribute: .centerX,
                         relatedBy: .equal,
                         toItem: view,
                         attribute: .centerX,
                         multiplier: 1,
                         constant: 0)
     ])
   }

这段代码可以工作并显示测试广告。然而，在GameScene.swift中，当我按下一个按钮时，我运行这段代码来尝试隐藏广告。

GameViewController().bannerView.isHidden = true

这将导致应用程序崩溃，"Fatal error: Unexpected found nil while implicitly unwrapping an Optional value"。而如果我改变它，它不会崩溃，但广告不会隐藏。

GameViewController().bannerView?.isHidden = true

然而在GameViewController中，如果我简单地将isHidden的值改为true，那么它就会工作。

bannerView.isHidden = true

无论如何，当我按下按钮时，能够在GameScene.swift中隐藏横幅广告？

Answer 1

当你在调用 GameViewController() 您正在创建一个新的 GameViewController.

关于 GameViewController().bannerView 您正在访问的 bannerView 由于它是一个可选的值，没有在这个实例上设置，当你试图访问它时，会导致崩溃。

你需要的是访问主 GameViewController在这里，你有 bannerView 集。

有两个简单的方法可以调用 GameViewController 其他类的函数：通过 delegate 或通过使类实例 static.

//   DELEGATE
//
// You have access only to the functions you declared inside the procotol. 
// Only the classes that conforms to that protocol have access to the functions.
//
// GameViewController.swift

protocol GameView_Delegate
{
    func hide_ads()
}

class GameViewController: UIViewController, GameView_Delegate
{
    override func viewDidLoad()
    {

    //   ... 

    if let view = self.view as! SKView?
    {
        if let scene = SKScene(fileNamed: "GameScene")
        {        
            scene.scaleMode = .aspectFill

            // pass protocol reference
            scene.gv_delegate = self
        }

        view.presentScene(scene)
     }

    // ...

    }

    func hide_ads()
    {
        // hide ads code

        bannerView.isHidden = true
    }
}

// GameScene.swift

class GameScene: SKScene
{
    var gv_delegate : GameView_Delegate!

    func settings()
    {
        // call function hide_ads from GameViewController
        gv_delegate.hide_ads()
    }

    func lost_scene()
    {
        let transition = SKTransition.fade(with: UIColor.white, duration: 1.0)
        let next_scene = LostScene()
        next_scene.anchorPoint = CGPoint(x: 0.5, y: 0.5)
        next_scene.scaleMode = self.scaleMode
        next_scene.size = self.size

        // before moving to next scene, we must pass the delegate, so we
        // don't  lose the connection with the GameViewController
        next_scene.gv_delegate = gv_delegate
        self.view?.presentScene(next_scene, transition: transition)
    }
}

// LostScene.swift

class LostScene: SKScene
{
    var gv_delegate : GameView_Delegate!

    func settings()
    {
        // call function hide_ads from GameViewController
        gv_delegate.hide_ads()
    }

    func game_scene()
    {
        let transition = SKTransition.fade(with: UIColor.white, duration: 1.0)
        let next_scene = GameScene()
        next_scene.anchorPoint = CGPoint(x: 0.5, y: 0.5)
        next_scene.scaleMode = self.scaleMode
        next_scene.size = self.size

        // before moving to next scene, we must pass the delegate, so we
        // don't lose the connection with the GameViewController
        next_scene.gv_delegate = gv_delegate
        self.view?.presentScene(next_scene, transition: transition)
    }
}

当你进入一个新的场景时，例如 LostScene昔日的场景 GameScene 在我们的例子中，是deallocated(清空所有变量，销毁所有引用)，并建立一个新的 GameScene 实例被创建并显示在屏幕上。在过渡到新的场景之前，你应该传递引用，这样你就不会失去与新场景的连接。GameViewController (如我的例子)。

// STATIC
//
// the properties and functions are available from everywhere
//
// GameViewController.swift

class GameViewController: UIViewController
{
    static var shared : GameViewController!

    override func viewDidLoad()
    {
        super.viewDidLoad()

        GameViewController.shared = self

        // ...

    }

    func hide_ads()
    {
        // hide ads code
        bannerView.isHidden = true
    }
}


// GameScene.swift

class GameScene: SKScene
{
    func settings()
    {
        // call function hide_ads from GameViewController

        GameViewController.shared.hide_ads()
        // or GameViewController.shared.bannerView.isHidden = true
    }
}

Answer 2

你正在创建一个新的 GameViewController 和切换它的 bannerView's isHidden 属性。你应该把 isHidden 的财产 bannerView 的 GameViewController 的实例。

Answer 3

如果有人想知道，这是我找到的隐藏横幅的解决方案。

"在GameViewController.swift文件中处理所有的横幅内容" "在那里，为bannerView变量分配一个标签值 在那里里面，为bannerView变量分配一个标签值。然后当场景加载时，使用标签id加载bannerView，然后将其.isHidden属性设置为true"

GameViewController.swift

bannerView.tag = 100

GameScene.swift

// hide banner
let bannerView = self.view?.viewWithTag(100) as! GADBannerView?
bannerView?.isHidden = true

// show banner
let bannerView = self.view?.viewWithTag(100) as! GADBannerView?
bannerView?.isHidden = false