Xcode and Vuforia/Unity integration

Hi,

I have followed the guide on how to integrate Unity/vuforia in XCode. And it works. But I need to have some viewcontrollers that also use the camera. 

My problem now is that the camera is already in use by vuforia. How can I make the unity/vuforia viewcontroller initialize the camera when I want it to and not on app start up? (And disable it when moving to next view controller so I can use it again.)

please help.

kind regards, Eric de Haan