warning: duplicate protocol definition of '...' is ignored

Check to make sure you don't have the header file added in your project twice, or two different files that both implement the protocol. This is what caused the warning to appear for me.

Yes I had the same problem. I was unable to find the duplicate header file in Xcode project. But when i went through the finder from the Xcode i found the 2 header file of the protocol in the project. Deleting one solved the problem. Thanks.