ios前端和后台js交互

import WebKit

class ViewController: UIViewController {
    var webView: WKWebView!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        webView = WKWebView(frame: self.view.frame)
        self.view.addSubview(webView)
        
        if let url = URL(string: "https://example.com") {
            let request = URLRequest(url: url)
            webView.load(request)
        }
    }

    func callJavaScript() {
        let jsString = "alert('Hello from Swift!');"
        webView.evaluateJavaScript(jsString) { (result, error) in
            if let error = error {
                print("Error: \(error)")
            } else {
                print("JavaScript executed successfully")
            }
        }
    }
}

import WebKit

class ViewController: UIViewController, WKScriptMessageHandler {
    var webView: WKWebView!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let contentController = WKUserContentController()
        contentController.add(self, name: "nativeApp")

        let config = WKWebViewConfiguration()
        config.userContentController = contentController

        webView = WKWebView(frame: self.view.frame, configuration: config)
        self.view.addSubview(webView)
        
        if let url = URL(string: "https://example.com") {
            let request = URLRequest(url: url)
            webView.load(request)
        }
    }

    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        if message.name == "nativeApp", let messageBody = message.body as? String {
            print("Received message from JavaScript: \(messageBody)")
        }
    }
}

window.webkit.messageHandlers.nativeApp.postMessage('Hello from JavaScript!');