從AppDelegate調用委托函數不起作用

Question

我正在嘗試在AppDelegate中調用委托函數，但似乎從未調用過它。

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate,appdelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        if let navigationController = window?.rootViewController, let
            viewController = navigationController.childViewControllers.first as? ViewController {
            viewController.delegate = self
        }
        // Override point for customization after application launch.
        return true
    }

    func callfromDelegte(indicator: UIActivityIndicatorView) {
        indicator.stopAnimating()
    }

ViewController-：

import UIKit

protocol appdelegate:class {
    func callfromDelegte(indicator:UIActivityIndicatorView)
}
class ViewController: UIViewController {

    @IBOutlet weak var indicator: UIActivityIndicatorView!
   weak var delegate:appdelegate?

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        indicator.startAnimating()
        indicator.hidesWhenStopped = true
    }

    @IBAction func rotateAction(_ sender: UIButton) {
        if delegate != nil{
        delegate?.callfromDelegte(indicator: indicator)
        }
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

委托始終為零，它永遠不會進入函數內部。 我現在不了解代表什么？ 如何從控制器類的AppDelegate內部調用Google GIDSignInDelegate及其委托函數？ 我知道這可能是一個非常愚蠢的問題，但我仍然想知道。

好的，因為我還沒有將我的控制器嵌入navigationController，所以它能正常工作。 因此， 如果讓它就不會進去。 它像這樣簡單地工作：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
//        if let navigationController = window?.rootViewController, let
//            viewController = navigationController.childViewControllers.first as? ViewController {
//            viewController.delegate = self
//        }
        // Override point for customization after application launch.

        let controller = window?.rootViewController as! ViewController
        controller.delegate = self
        return true
    }

Answer 1

你不能創建Viewcontroller直接對象，並設置delegate你的內部app delegate 。 您需要首先訪問Viewcontroller對象，因為它位於rootViewController內部，因此您需要像這樣實現

if let navigationController = window?.rootViewController, let 
   viewController = navigationController.childViewControllers.first as? ViewController {
 viewController.delegate = self
}

Answer 2

您可以嘗試從共享應用程序獲取AppDelegate實例。 希望對你有幫助

這是Swift 3

@IBAction func rotateAction(_ sender: UIButton) {
        let delegate = UIApplication.shared.delegate as? AppDelegate

        delegate?.callfromDelegte(indicator: indicator)
}