iOS - 如何以编程方式创建 WKWebView 后退按钮？

Question

我正在尝试为我的 iOS WKWebView 应用程序创建一个后退按钮，这样当用户单击该按钮时，它会将他们带到上一个 WKWebView 页面。我找到了许多关于如何使用 IB 而不是直接代码的教程。这是我目前所拥有的：

原始 ViewController.swift：

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {

    private var webView: WKWebView!

    let wv = WKWebView(frame: UIScreen.mainScreen().bounds) //needed for working webview

    self.webView = WKWebView(frame: frame)
    self.webView.navigationDelegate = self

    func rightbutton(text: String, action: Selector) {
        let rightButton = UIBarButtonItem(title: text, style: .Plain, target: self, action: action)
        self.navigationItem.rightBarButtonItem = rightButton
    }

    func action() {
        if self.webView.canGoBack {
            print ("Can go back")
            self.webView.goBack()
            self.webView.reload()

        } else {
            print ( "Can't go back")
        }
    }


    override func viewDidLoad() {
        super.viewDidLoad()
        guard let url =  NSURL(string: "http://communionchapelefca.org/app-home") else { return }
        wv.navigationDelegate = self
        wv.loadRequest(NSURLRequest(URL: url))
        view.addSubview(wv)


        webView.goBack()
        webView.reload()



        prefButton()
        //backButton()

        NSNotificationCenter.defaultCenter().addObserver(self,
            selector: "receiveNotification:",
            name: "BeaconServiceRegionEnter",
            object: nil)

        NSNotificationCenter.defaultCenter().addObserver(self,
            selector: "receiveNotification:",
            name: "BeaconServiceRegionUpdate",
            object: nil)

        NSNotificationCenter.defaultCenter().addObserver(self,
            selector: "receiveNotification:",
            name: "BeaconServiceRegionExit",
            object: nil)

    }

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

    func prefButton () {
        let image = UIImage(named: "icon-pref128") as UIImage?
        let button   = UIButton(type: UIButtonType.Custom) as UIButton
        let screenSize: CGRect = UIScreen.mainScreen().bounds
        let screenWidth = screenSize.width
        let screenHeight = screenSize.height

        button.frame = CGRectMake(screenWidth * 0.85, screenHeight * 0.90, 56, 56) // (X, Y, Height, Width)
        button.setImage(image, forState: .Normal)
        button.addTarget(self, action: "buttonClicked:", forControlEvents:.TouchUpInside)
        self.view.addSubview(button)
    }

    func buttonClicked(sender:UIButton)
    {
        UIApplication.sharedApplication().openURL(NSURL(string: UIApplicationOpenSettingsURLString)!)
    }

    func receiveNotification(notification: NSNotification) {
        print(notification.userInfo)
    }

    func webView(webView: WKWebView, decidePolicyForNavigationAction navigationAction: WKNavigationAction, decisionHandler: (WKNavigationActionPolicy) -> Void) {
        if navigationAction.navigationType == .LinkActivated  {
            if let newURL = navigationAction.request.URL,
                host = newURL.host where !host.containsString("communionchapelefca.org") &&
                    UIApplication.sharedApplication().canOpenURL(newURL) {
                        if UIApplication.sharedApplication().openURL(newURL) {
                            print(newURL)
                            print("Redirected to browser. No need to open it locally")
                            decisionHandler(.Cancel)
                        } else {
                            print("browser can not url. allow it to open locally")
                            decisionHandler(.Allow)
                        }
            } else {
                print("Open it locally")
                decisionHandler(.Allow)
            }
        } else {
            print("not a user click")
            decisionHandler(.Allow)
        }
    }

}

有什么建议吗？提前致谢。

编辑：附加整个 ViewController 而不是 sn-p 代码。

EDIT2：k8mil 的回答很接近，因为他的回答没有加载初始 URL。以下是他回答的唯一调整：

private func createWebView() {
        guard let url = NSURL(string: "http://communionchapelefca.org/app-home") else { return }
        let frame  = UIScreen.mainScreen().bounds // or different frame created using CGRectMake(x,y,width,height)
        self.webView = WKWebView(frame: frame)
        self.webView.navigationDelegate = self
        self.webView.loadRequest(NSURLRequest(URL: url))
        self.view.addSubview(self.webView)
    }

Answer 1

尝试在 WKWebView 实例上调用 webView.goBack() 方法，而不是 WKWebView.goBack()。同样在goBack() 之后，您可以调用webView.reload() 方法来确保您在正确的页面上。

我稍微修改了你的代码

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {

private var webView: WKWebView!

override func viewDidLoad() {
    super.viewDidLoad()
    guard let url = NSURL(string: "http://communionchapelefca.org/app-home") else {
        return
    }

    //create WebView and Back button
    createWebView()
    backButton()


    prefButton()


    NSNotificationCenter.defaultCenter().addObserver(self,
            selector: "receiveNotification:",
            name: "BeaconServiceRegionEnter",
            object: nil)

    NSNotificationCenter.defaultCenter().addObserver(self,
            selector: "receiveNotification:",
            name: "BeaconServiceRegionUpdate",
            object: nil)

    NSNotificationCenter.defaultCenter().addObserver(self,
            selector: "receiveNotification:",
            name: "BeaconServiceRegionExit",
            object: nil)

}


private func createWebView() {
    let frame  = UIScreen.mainScreen().bounds // or different frame created using CGRectMake(x,y,width,height)
    self.webView = WKWebView(frame: frame)
    self.webView.navigationDelegate = self
    self.view.addSubview(self.webView)
}

func addBackButton(text: String, action: Selector) {
    //this function will add Button on your navigation bar e

    let rightButton = UIBarButtonItem(title: text, style: .Plain, target: self, action: action)
    self.navigationItem.rightBarButtonItem = rightButton
}


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

func prefButton() {
    let image = UIImage(named: "icon-pref128") as UIImage?
    let button = UIButton(type: UIButtonType.Custom) as UIButton
    let screenSize: CGRect = UIScreen.mainScreen().bounds
    let screenWidth = screenSize.width
    let screenHeight = screenSize.height

    button.frame = CGRectMake(screenWidth * 0.85, screenHeight * 0.90, 56, 56) // (X, Y, Height, Width)
    button.setImage(image, forState: .Normal)
    button.addTarget(self, action: "buttonClicked:", forControlEvents: .TouchUpInside)
    self.view.addSubview(button)
}

func backButton() {
    let image = UIImage(named: "icon-back") as UIImage?
    let button = UIButton(type: UIButtonType.Custom) as UIButton
    let screenSize: CGRect = UIScreen.mainScreen().bounds
    let screenWidth = screenSize.width
    let screenHeight = screenSize.height

    button.frame = CGRectMake(screenWidth * 0.85, screenHeight * 0.90, 56, 56) // (X, Y, Height, Width)
    button.setImage(image, forState: .Normal)
    button.addTarget(self, action: "customGoBack:", forControlEvents: .TouchUpInside)
    self.view.addSubview(button)
}

func customGoBack(sender: UIButton) {
    if self.webView.canGoBack {
        print("Can go back")
        self.webView.goBack()
        self.webView.reload()
    } else {
        print("Can't go back")
    }
}

func buttonClicked(sender: UIButton) {
    UIApplication.sharedApplication().openURL(NSURL(string: UIApplicationOpenSettingsURLString)!)
}

func receiveNotification(notification: NSNotification) {
    print(notification.userInfo)
}

func webView(webView: WKWebView, decidePolicyForNavigationAction navigationAction: WKNavigationAction, decisionHandler: (WKNavigationActionPolicy) -> Void) {
    if navigationAction.navigationType == .LinkActivated {
        if let newURL = navigationAction.request.URL,
        host = newURL.host where !host.containsString("communionchapelefca.org") &&
                UIApplication.sharedApplication().canOpenURL(newURL) {
            if UIApplication.sharedApplication().openURL(newURL) {
                print(newURL)
                print("Redirected to browser. No need to open it locally")
                decisionHandler(.Cancel)
            } else {
                print("browser can not url. allow it to open locally")
                decisionHandler(.Allow)
            }
        } else {
            print("Open it locally")
            decisionHandler(.Allow)
        }
    } else {
        print("not a user click")
        decisionHandler(.Allow)
    }
}

}

你也不需要 WKWebView 的另一个实例，因为你之前已经声明过：

private var webView : WKWebView!

所以没有必要：

wv.navigationDelegate = self
wv.loadRequest(NSURLRequest(URL: url))  
view.addSubview(wv)

对我来说它有效。

希望对你有帮助:)