Check programmatically if contact allows FaceTime in Objective-C or Swift

Question

As in the headers, I am working on a contact application. I would like to know if there is a way to find out if contacts are available through FaceTime? Is there a public API for this? (Note: Solutions like ChatKit.framework for iMessage are not really acceptable, i.e. private APIs)

UPDATE: found here a message that partially answers the question: FaceTime programmatically

UPDATE # 2: using the @ "// facetime:" schema doesn't seem to work at all, since I always get true in the opposite

UIApplication.sharedApplication().canOpenURL(NSURL(string: "facetime://0000000000")!)