ios - swift 3 WKWebView 委托(delegate) WKNavigationDelegate 模糊方法

我创建了一个名为JSBridge的类，这个类实现了WKNavigationDelegate，我在protocol方法中做了一些自定义的东西，然后调用另一个UIViewController的默认WKNavigationDelegate，例如WebViewController又名webViewDelegate，所以我必须这样做

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
    guard let webViewDelegate = webViewDelegate , self.webView == webView else {
        decisionHandler(.allow)
        return
    }

    //do something here then call `WebViewController`'s implementation
    if webViewDelegate.responds(to: #selector(webViewDelegate.webView(_:decidePolicyFor:decisionHandler)) {
            webViewDelegate.webView!(webView, decidePolicyFor: navigationAction, decisionHandler: decisionHandler)
        } else {
            decisionHandler(.allow)
        }
}

func webView(_ webView: WKWebView, decidePolicyFor navigationResponse: WKNavigationResponse, decisionHandler: @escaping (WKNavigationResponsePolicy) -> Void) {
    guard let webViewDelegate = webViewDelegate , self.webView == webView else {
        decisionHandler(.allow)
        return
    }

    //do something here then 
    if webViewDelegate.responds(to: #selector(webViewDelegate.webView(_:decidePolicyFor:decisionHandler)) {
        webViewDelegate.webView!(webView, decidePolicyFor: navigationResponse, decisionHandler: decisionHandler)
    } else {
        decisionHandler(.allow)
    }
}

我的问题出在 xcode8(swift3) 中，编译器给了我错误: 'webView(_:decidePolicyFor:decisionHandler'的歧义使用，它们与编译器同名

func webView(_ webView: WKWebView, decidePolicyFor navigationResponse: WKNavigationResponse, decisionHandler: @escaping (WKNavigationResponsePolicy) -> Void)
func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void)

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Best Answer-推荐答案

您可以使用 as 从一些模棱两可的方法中选择一种:

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
    guard let webViewDelegate = webViewDelegate , self.webView == webView else {
        decisionHandler(.allow)
        return
    }

    typealias WKNavigationActionMethodType = (WKWebView,WKNavigationAction,@escaping(WKNavigationActionPolicy)->Void) -> Void
    if webViewDelegate.responds(to: #selector(webView(_:decidePolicyFor:decisionHandler as WKNavigationActionMethodType)) {
        webViewDelegate.webView!(webView, decidePolicyFor: navigationAction, decisionHandler: decisionHandler)
    } else {
        decisionHandler(.allow)
    }
}

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另一种处理这种情况的方法是“避免使用 responds(to 并使用可选链接”:

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
    guard let webViewDelegate = webViewDelegate , self.webView == webView else {
        decisionHandler(.allow)
        return
    }

    if webViewDelegate.webView?(webView, decidePolicyFor: navigationAction, decisionHandler: decisionHandler) == nil {
        decisionHandler(.allow)
    }
}

委托(delegate)方法的返回类型是Void，所以它的Optional链结结果是Void?类型。在您的情况下，只有在实例中未实现可选方法时，它才会变为 nil 。因此，将结果与 nil 进行比较是在检查可选方法是否已实现(并实际调用)。

关于ios - swift 3 WKWebView 委托(delegate) WKNavigationDelegate 模糊方法，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39658358/