代理方法中實現：
// 在收到響應後，決定是否跳轉
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{
WKNavigationResponsePolicy actionPolicy = WKNavigationResponsePolicyAllow;
//這句是必須加上的，不然會異常
decisionHandler(actionPolicy);
}
// 在發送請求之前，決定是否跳轉
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler{
self.title = webView.title;
WKNavigationActionPolicy actionPolicy = WKNavigationActionPolicyAllow;
//這句是必須加上的，不然會異常
decisionHandler(actionPolicy);
}