App installation failed: Unknown Error Xcode 7

Question

My app runs fine in the simulator, but when I try to install it on my iPhone it says

App installation failed: An unknown error has occurred.

Answer 1

I also had this problem, in device log it said that code signing failed for my app extension ....appex. I went to my App Target -> Build phases -> Embed App Extensions and checked Copy only when installing, after that I could install the app on the phone.