I drag a Round Rect Button to the position of the right Bar Button Item, and set an image to the Round Rect Button. All works well, except the warning \"Plain Style unsuppor
After you are sure that you have all your bar buttons in the storyboard set to anything but plain, make sure you do a git commit and delete derived data. I spent forever trying to figure out why the problem wasn't fixing itself, and deleting the derived data folder fixed it for me.
I stopped the warning about Plain Style by poking around in the Document Outline. That was showing my Navigation Item, and within that 2 Bar Button Items, and within each of those a Button. The offending setting was on the Bar Button Item. In its attributes inspector I changed Style from Plain to Done, and the warning went away. Note: I am using XCode 5.