Unfortunately, client authentication is not something doable out-of-the-box with the Cordova framework and is currently not supported in AppBuilder also. The native UIWebView in iOS could not intercept a stored certificate and send it to the server through AJAX calls.
The general recommendation in such cases is to construct a Cordova plugin that handles the client and use native Objective-C calls implemented in the plugin instead of jQuery.ajax(). Here is a very interesting blog post on this matter that outlines the whole workflow in Cordova. Another useful information about the native part can be found here and here.
In addition, we believe that a client side authentication is a very meaningful scenario and we would therefore like to support it within AppBuilder. The development team is currently investigating the options for implementing this without a plugin but with a suitable native protocol that an AJAX request can utilize. However, as this task requires an extensive research, our team needs more time.
I will make sure to update this thread as soon as we have more progress on the task.
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