I am using Ionic 2 and the Wikitude plugin for Cordova in order to create an augmented reality app. I have used the Wikitude starter app here (http://market.ionic.io/starters/wikitude-ionic-2-starter-app) and I would like to know how I can open the Wikitude camera viewer inside an Ionic view (so that I can overlay Ionic buttons and a menu header).
Currently, Wikitude is loading in a new view which is working fine, but I would like to integrate the software with the rest of the app and make it feel less separate.
Currently there is no way to customise the Wikitude iOS Cordova plugin behaviour when it comes to view presentation. You would need to change the Wikitude Cordova iOS plugin itself (Objective-C code) to not present a new view controller but instead just add the WTArchitectView to your view hierarchy.
Regarding your second question: You can use the Wikitude iOS SDK Objective-C API directly to start rendering/load Architect Worlds. How your integrate this in your own app I can't tell you since I don't know any detail about Ionic.
Maybe you want/need to write your own Cordova plugin/Ionic plugin to use/present the Wikitude SDK in a way that fits into your application flow.