Declaring required properties

Not surprisingly, we can also add properties to a protocol. Protocol properties must be declared with var, and can be declared to be settable (that is, read--only) or settable and gettable (meaning read and write).

Let's add a couple of properties to the TalkativePerson protocol:

protocol TalkativePerson: Talkative 
{ 
   var name: String { get } 
   var address: String { getset} 
} 

TalkativePerson contains everything from talkative, and adds two further properties. We assume (for the sake of the demonstration) that people don't change their names, but do change their addresses.