[WKWebViewJavascriptBridge webView:decidePolicyForNavigationAction:decisionHandler:] was called m...

WKWebViewJavascriptBridge.m文件中decisionHandler(WKNavigationActionPolicyCancel);后加return;

- (void)webView:(WKWebView *)webView
decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction
decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    if (webView != _webView) { return; }
    NSURL *url = navigationAction.request.URL;
    __strong typeof(_webViewDelegate) strongDelegate = _webViewDelegate;

    if ([_base isCorrectProcotocolScheme:url]) {
        if ([_base isBridgeLoadedURL:url]) {
            [_base injectJavascriptFile];
        } else if ([_base isQueueMessageURL:url]) {
            [self WKFlushMessageQueue];
        } else {
            [_base logUnkownMessage:url];
        }
        decisionHandler(WKNavigationActionPolicyCancel);
        // 我猜测主要原因是 Xcode9上，decisionHandler() 这个block回调，不允许多次被调用；所以添加了return
        return;
    }
    
    if (strongDelegate && [strongDelegate respondsToSelector:@selector(webView:decidePolicyForNavigationAction:decisionHandler:)]) {
        [_webViewDelegate webView:webView decidePolicyForNavigationAction:navigationAction decisionHandler:decisionHandler];
    } else {
        decisionHandler(WKNavigationActionPolicyAllow);
    }
}