This is a very strange issue. Happening both in the simulator AND on iPhone 6 and 6 Plus devices.
I am getting a 1px black line at the very top and very bottom of every page of my app. It is just above the status bar at the top and it is not just when there is a nav bar. It is on every page, even when it is too hard to see, I screenshot the page and zoom and can see the thin black lines at the top and bottom.
Black line at the top:
Black line at the bottom: