Swift 3.0 WKWebView 如何拦截网页端发出的协议

Question

最近想研究一下 Native 和 Web 之间的交互，了解了一下 Web 端可以发送类似 command://do?hello=world 的自定义协议来向 Native 端交互，然后通过 delegate 函数在 Native 层接收到通知。

写了下面这个非常简单的 demo 后，发现 webView() 方法并没有执行，本人对 iOS 和 Swift 都不是很了解，不知道问题出在哪里。

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate, WKUIDelegate {
    
    var webView: WKWebView?
    var configure: WKWebViewConfiguration?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.configure = WKWebViewConfiguration()
        
        self.configure?.preferences = WKPreferences()
        self.configure?.preferences.javaScriptEnabled = true
        
        self.webView = WKWebView(frame: self.view.bounds, configuration: self.configure!)
        self.view.addSubview(webView!)

        self.webView?.navigationDelegate = self
        self.webView?.uiDelegate = self
    }
    
    override func viewWillAppear(_ animated: Bool) {
        print("viewWillAppear")
        super.viewWillAppear(animated)
        self.webView?.loadResource(string: "web-content/index")
    }
    
    override func didReceiveMemoryWarning() {
        print("didReceiveMemoryWarning")
        super.didReceiveMemoryWarning()
    }
    
    func webView(webView: WKWebView, shouldStartLoadWithRequest request: NSURLRequest, navigationType: UIWebViewNavigationType) -> Void {
        print("webView")
    }
    
    func webViewDidStartLoad(webView: WKWebView) {
        print("webViewDidStartLoad")
    }
}

extension WKWebView {
    func loadUrl(string: String) {
        if let url = URL(string: string) {
            load(URLRequest(url: url))
        }
    }
    
    func loadResource(string: String) {
        let url = Bundle.main.url(forResource: string, withExtension: "html")!
        let request: NSURLRequest = NSURLRequest(url: url as URL)
        
        load(request as URLRequest);
    }
}

主要目的就是当 Web 端发起协议的时候，Native 能接收到信息。

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后面问朋友后发现是 delegate 函数错了，应该是这样才对：

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
    print("hello world")
    decisionHandler(WKNavigationActionPolicy.allow)
}