You're using an old version. Go to github, find the latest version number and upgrade to that. At the time of writing that is version 0.22.0, which is still months old so will still have some build warnings, but you don't really need to worry about them (Xcode is being more specific about reporting is all, that doesn't mean things shouldn't be fixed, and they are being fixed, but most aren't an issue for you).
If you really don't like the warnings, switching to the HEAD of the development branch will reduce most issues as it has the most up-to-date code.