First, determine which version(s) of Cocoapods you have installed by running this in Terminal:
gem list --local | grep cocoapods
You see output similar to this:
cocoapods (0.27.1, 0.20.2)
cocoapods-core (0.27.1, 0.20.2)
cocoapods-downloader (0.2.0, 0.1.2)