I think by default it now seems to install WKWebView on ionic or cordova projects, at least in my case anyway (it appears as a plugin in the plugins folder). So I uninstall the plugin and added this line into my config.xml:
<preference name="CordovaWebViewEngine" value="CDVUIWebViewEngine" />
I then set this globally for my HTTP provider:
$httpProvider.defaults.withCredentials = true;
or this can be done this way for each HTTP requests you have:
$http.post(url, {withCredentials: true, ...})
I then set this on my .php/server files:
header("Access-Control-Allow-Origin: http://localhost:8100"); // make sure this is the same on the client side
header("Access-Control-Allow-Headers: content-type,authorization");
header("Access-Control-Allow-Credentials: true");
The fixes mentioned above allows me to keep the same cookies/session throughout each page/requests in my application.
I hope this helps.
Edit:
From what I could find when I was having this issue, there was no way of persisting the cookies/session using WKWebView as Apple has not added a fix (I could be completely wrong, it's just what I found at that point. I think you either had to revert back to UIWebView or use a different method entirely.