Question

我创建了一个名为JSBridge的类，这个类实现了WKNavigationDelegate，我在协议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)
    }
}

我的问题是在xcode8（swift3）中编译器给我错误： Ambiguous use of 'webView(_:decidePolicyFor:decisionHandler:)'，它们与编译器具有相同的名称

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

Answer 1

您可以使用as从一些不明确的方法中选择一个：

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)
    }
}

另一种处理此类情况的方法是＆＃34;避免使用responds(to:)并使用可选链接＆＃34;：

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)
    }
}

委托方法的返回类型为Void，因此其可选链接结果的类型为Void?。在您的情况下，仅当实例中未实现可选方法时，它才会变为nil。因此，将结果与nil进行比较是检查可选方法是否已实现（并实际调用）。

swift 3 WKWebView委托WKNavigationDelegate模糊方法

1 个答案: