wkwebview a target="_blank" 打不開鏈接的解決方案

- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler
{
    //this is a 'new window action' (aka target="_blank") > open this URL externally. If we´re doing nothing here, WKWebView will also just do nothing. Maybe this will change in a later stage of the iOS 8 Beta
    if (!navigationAction.targetFrame) { 
        NSURL *url = navigationAction.request.URL;
        UIApplication *app = [UIApplication sharedApplication];
        if ([app canOpenURL:url]) {
            [app openURL:url];
        }
    }
    decisionHandler(WKNavigationActionPolicyAllow);
}