错误的原因是： 在方法

 - (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler 
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中未实现 decisionHandler(WKNavigationActionPolicyCancel） block 的回调。

代理方法中，未实现block的回调

放开上图中的注释部分就可以了。

// 必须实现decisionHandler的回调，否则就会报错
    if (navigationAction.navigationType == WKNavigationTypeLinkActivated) {
        decisionHandler(WKNavigationActionPolicyCancel);
        NSLog(@"WKNavigationActionPolicyCancel");
    } else {
        decisionHandler(WKNavigationActionPolicyAllow);
        NSLog(@"WKNavigationActionPolicyAllow");
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另外一个代理方法也是，需要实现block的回调，不然也会报错。 这个方法是在加载网络页面的时候调用。

- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler
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错误提示如下： reason: 'Completion handler passed to -[JavaScriptCallOCViewController webView:decidePolicyForNavigationResponse:decisionHandler:] was not called'

#pragma mark 在收到响应后，决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler
    NSLog(@"6->在收到响应后，决定是否跳转");
    NSLog(@"navigationResponse = %@", navigationResponse);
    NSLog(@"navigationResponse.response = %@", navigationResponse.response);
    // 必须实现decisionHandler的回调，否则就会报错
    decisionHandler(WKNavigationResponsePolicyAllow);
    NSLog(@"WKNavigationResponsePolicyAllow");