Swift与JS通过WKWebView互调

创建WKWebView

lazy var webView: WKWebView = {
    // 创建WKPreferences
    let preferences = WKPreferences()
    // 开启js
    preferences.javaScriptEnabled = true
    // 创建WKWebViewConfiguration
    let configuration = WKWebViewConfiguration()
    // 设置WKWebViewConfiguration的WKPreferences
    configuration.preferences = preferences
    // 创建WKUserContentController
    let userContentController = WKUserContentController()
    // 配置WKWebViewConfiguration的WKUserContentController
    configuration.userContentController = userContentController
    // 给WKWebView与Swift交互起一个名字：callbackHandler，WKWebView给Swift发消息的时候会用到
    // 此句要求实现WKScriptMessageHandler协议
    configuration.userContentController.add(self, name: "callbackHandler")
    
    // 创建WKWebView
    var webView = WKWebView(frame: self.view.frame, configuration: configuration)
    // 让webview翻动有回弹效果
    webView.scrollView.bounces = true
    // 只允许webview上下滚动
    webView.scrollView.alwaysBounceVertical = true    
    // 此句要求实现WKNavigationDelegate协议
    webView.navigationDelegate = self
    
    return webView
}()

创建HTML

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0,user-scalable=no"/>
    </head>
    <body>
        iOS传过来的值：<span id="name"></span>
        <button onclick="responseSwift()">响应iOS</button>
        <script type="text/javascript">
            // 给Swift调用
            function sayHello(name) {
                document.getElementById("name").innerHTML = name
                return "Swift你好！"
            }
            
            // 调用Swift方法
            function responseSwift() {
                // 这里的callbackHandler是创建WKWebViewConfiguration时定义的
                window.webkit.messageHandlers.callbackHandler.postMessage("JS发送消息给Swift")
            }
        </script>
    </body>
</html>

实现两个协议

WKNavigationDelegate：判断页面加载完成，只有在页面加载完成后才能在实现 Swift 调用 JS。WKWebView调用JS：

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
    // sayHello()是JS的方法
    webView.evaluateJavaScript("sayHello('WebView你好！')") { (result, err) in
        print(result, err)
    }
}

WKScriptMessageHandler：JS 调用 Swift 时需要用到协议中的一个方法来。JS调用WKWebView：

func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
    print(message.body)
}

##完整代码

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate, WKScriptMessageHandler {
    
    lazy var webView: WKWebView = {
        // 创建WKPreferences
        let preferences = WKPreferences()
        // 开启js
        preferences.javaScriptEnabled = true
        // 创建WKWebViewConfiguration
        let configuration = WKWebViewConfiguration()
        // 设置WKWebViewConfiguration的WKPreferences
        configuration.preferences = preferences
        // 创建WKUserContentController
        let userContentController = WKUserContentController()
        // 配置WKWebViewConfiguration的WKUserContentController
        configuration.userContentController = userContentController
        // 给WKWebView与Swift交互起一个名字：callbackHandler，WKWebView给Swift发消息的时候会用到
        // 此句要求实现WKScriptMessageHandler协议
        configuration.userContentController.add(self, name: "callbackHandler")
        
        // 创建WKWebView
        var webView = WKWebView(frame: self.view.frame, configuration: configuration)
        // 让webview翻动有回弹效果
        webView.scrollView.bounces = true
        // 只允许webview上下滚动
        webView.scrollView.alwaysBounceVertical = true
        
        // 此句要求实现WKNavigationDelegate协议
        webView.navigationDelegate = self
        
        return webView
    }()
    
    // 加载html
    let html = try! String(contentsOfFile: Bundle.main.path(forResource: "index", ofType: "html")!, encoding: String.Encoding.utf8)
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        title = "WebView与JS交互"
        view.addSubview(webView)
        
        webView.loadHTMLString(html, baseURL: nil)
    }
    
    // 加载完毕以后执行
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        // 调用JS方法
        webView.evaluateJavaScript("sayHello('WebView你好！')") { (result, err) in
            // result是JS返回的值
            print(result, err)
        }
    }
    
    // Swift方法，可以在JS中调用
    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        print(message.body)
    }
}

补充

拦截、并处理 alert()

extension ViewController: WKUIDelegate {
    
    // 读取window.alert()
    func webView(_ webView: WKWebView,
                 runJavaScriptAlertPanelWithMessage message: String,
                 initiatedByFrame frame: WKFrameInfo,
                 completionHandler: @escaping () -> Void) {
        // 处理
    }
}

拦截、并处理 confirm()

extension ViewController: WKUIDelegate {
    // 读取window.confirm()
    func webView(_ webView: WKWebView,
                 runJavaScriptConfirmPanelWithMessage message: String,
                 initiatedByFrame frame: WKFrameInfo,
                 completionHandler: @escaping (Bool) -> Void) {
        
        // 处理
    }
}

拦截、并处理 prompt()

extension ViewController: WKUIDelegate {
    // 1.读取widnow.prompt()
    func webView(_ webView: WKWebView,
                 runJavaScriptTextInputPanelWithPrompt prompt: String,
                 defaultText: String?,
                 initiatedByFrame frame: WKFrameInfo,
                 completionHandler: @escaping (String?) -> Void) {
        
        //处理
    }
}

注入脚本

// 创建WKUserContentController
let userContentController = WKUserContentController()
// 加载WKUserScript
let userScript = loadUserScript(with: "html/local_script")
// 注入WKUserScript
userContentController.addUserScript(userScript)



// addUserScript(_:) 接收一个WKUserScript对象
func loadUserScript(with path: String) -> WKUserScript {
    // 加载本地js文件
    let filePath = Bundle.main.path(forResource: path, ofType: "js")
    // js文件内容
    var script:String?
    
    do {
        script = try String(contentsOfFile: filePath!, encoding: String.Encoding.utf8)
    }
    catch {
        print("Cannot Load File")
    }
    
    return WKUserScript(source: script!, injectionTime: .atDocumentEnd, forMainFrameOnly: true)
}

防止内存泄漏

deinit {
    userContentController.removeScriptMessageHandler(forName: "callbackHandler")
}