Protocols in Objective C

Yes it is a protocol, and no it does not have instance variables. It has properties, which are just syntactic sugar for methods.

A property does not need to be backed by an instance variable at all; not in a class definition or a protocol (in the latter it can't just by the nature of how protocols work). All it cares about is that, for instance, in the case of a protocol named foo two methods exist if it's readwrite:

- foo - setFoo: 

Obviously, returning and taking the appropriate data type.