Why is WKWebView not opening links with target="_blank"?

Question

My solution is to cancel the navigation and load the request with loadRequest: again. This will be come the similar behavior like UIWebView which always open new window in the current frame.

Implement the WKUIDelegate delegate and set it to _webview.uiDelegate. Then implement:

- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures
{
  if (!navigationAction.targetFrame.isMainFrame) {
    [webView loadRequest:navigationAction.request];
  }

  return nil;
}

The answer from @Cloud Xu is the correct answer. Just for reference, here it is in Swift:

// this handles target=_blank links by opening them in the same view
func webView(webView: WKWebView!, createWebViewWithConfiguration configuration: WKWebViewConfiguration!, forNavigationAction navigationAction: WKNavigationAction!, windowFeatures: WKWindowFeatures!) -> WKWebView! {
    if navigationAction.targetFrame == nil {
        webView.loadRequest(navigationAction.request)
    }
    return nil
}

To use latest version of Swift 4.2+

import WebKit

Extend your class with WKUIDelegate

Set delegate for webview

self.webView.uiDelegate = self

Implement protocol method

func webView(_ webView: WKWebView, createWebViewWith configuration: WKWebViewConfiguration, for navigationAction: WKNavigationAction, windowFeatures: WKWindowFeatures) -> WKWebView? {
    if navigationAction.targetFrame == nil {
        webView.load(navigationAction.request)
    }
    return nil
}

Add yourself as the WKNavigationDelegate

_webView.navigationDelegate = self;

and implement following code in the delegate callback decidePolicyForNavigationAction:decisionHandler:

- (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);
}

P.S.: This code is from my little project STKWebKitViewController, which wraps a usable UI around WKWebView.

If you've already set the WKWebView.navigationDelegate

WKWebView.navigationDelegate = self;

you just need to implement:

- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler
{
    BOOL shouldLoad = [self shouldStartLoadWithRequest:navigationAction.request]; // check the url if necessary

    if (shouldLoad && navigationAction.targetFrame == nil) {
        // WKWebView ignores links that open in new window
        [webView loadRequest:navigationAction.request];
    }

    // always pass a policy to the decisionHandler
    decisionHandler(shouldLoad ? WKNavigationActionPolicyAllow : WKNavigationActionPolicyCancel);
}

this way you don't need to implement the WKUIDelegate method.

Cloud xu's answer solves my issue.

In case someone need the equivalent Swift(4.x/5.0) version, here is it:

func webView(_ webView: WKWebView, createWebViewWith configuration: WKWebViewConfiguration, for navigationAction: WKNavigationAction, windowFeatures: WKWindowFeatures) -> WKWebView? {
    if let frame = navigationAction.targetFrame,
        frame.isMainFrame {
        return nil
    }
    // for _blank target or non-mainFrame target
    webView.load(navigationAction.request)
    return nil
}

Of course you have to set webView.uiDelegate firstly.