Question

我想加载App时加载一个主viewController（ViewController）。当app再次进入前景以显示另一个viewController（ConfigViewController）但我尝试显示＆＃34; ViewController＆＃34;而不是＆＃34; ConfigViewController＆＃34;，我不知道为什么，任何人都可以提供帮助，谢谢。

的AppDelegate：

func applicationWillEnterForeground(_ application: UIApplication) {
    let notificationName = Notification.Name.UIApplicationWillEnterForeground
    NotificationCenter.default.post(name: notificationName, object: nil)
}

主ViewController：

 override func viewDidLoad() {
    super.viewDidLoad()

    let myBlog = "https://www.example.com/"
    let url = NSURL(string: myBlog)
    let request = NSURLRequest(url: url! as URL)

    // init and load request in webview.
    webView = WKWebView(frame: self.view.frame)
    webView.navigationDelegate = self
    webView.load(request as URLRequest)
    self.view.addSubview(webView)
    self.view.sendSubview(toBack: webView)

}

配置ViewController：

import UIKit

class ConfigViewController : UIViewController {


    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(
            self,
            selector: #selector(displayAlert),
            name: NSNotification.Name.UIApplicationWillEnterForeground,
            object: nil)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func displayAlert() {
        let alertController = UIAlertController(title: "Information", message: "Reactivate", preferredStyle: UIAlertControllerStyle.alert)
        let alertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil)

        alertController.addAction(alertAction)
        self.present(alertController, animated: true, completion: nil)

    }
}

Answer 1

在applicationWillEnterForeground中，您的viewcontrollers尚未出现在堆栈中。这将是。

为了满足您的需求，您可以：

func applicationWillEnterForeground(_ application: UIApplication) {
    self.window = UIWindow(frame: UIScreen.main.bounds)
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let vcMainView: ConfigViewController = mainStoryboard.instantiateViewController(withIdentifier: "ConfigViewController") as! ConfigViewController
    self.window?.rootViewController = vcMainView
    self.window?.makeKeyAndVisible()
}

然而，重要的是要查看您的didFinishLaunchingWithOptions中是否有人在调用另一个VC。

可以肯定的是，每次应用程序变为活动状态时，此代码都会调用ConfigViewController。如果您需要处理必须显示的位置和时间，这不是正确的方法。

applicationWillEnterForeground无法调用加载ViewController

1 个答案: