I came across some articles saying that Travis CI supports RubyMotion. However, I don't want to use Travis CI. I would like to use Codeship. Is this possible? What can I do to make this happen?
The only one that I'm aware of that supports RubyMotion is Travis. :-/
And it's more about the fact than you need OS X, almost no one has support for OS X.
Codeship does not support RM or anything iOS, unfortunately. I wish they did!
CircleCi is the only CI service I know that has support for iOS apps.