I am trying to run a Swift app on my iPhone 4s. It works fine on the simulator, and my friend can successfully run it on his iPhone 4s. I have iOS 8 and the official release
Xcode 7.2, iOS 9.2 on one device, 9.0 on other. Both had the error. No idea what changed that caused it, but the solutions above for the WWDR were correct for me. Install that cert and problem solved.