How to create generic protocols in Swift? -

i'd create protocol method takes generic input , returns generic value.

this i've tried far, produces syntax error.

use of undeclared identifier t.

what doing wrong?

protocol apimapperprotocol {     func mapfromsource(t) -> u }  class usermapper: nsobject, apimapperprotocol {     func mapfromsource(data: nsdictionary) -> usermodel {         var user = usermodel() usermodel         var accountsdata:nsarray = data["accounts"] nsarray              return user     }  } 

it's little different protocols. @ "associated types" in apple's documentation.

this how use in example

protocol apimapperprotocol {     associatedtype t     associatedtype u     func mapfromsource(t) -> u }  class usermapper: nsobject, apimapperprotocol {     typealias t = nsdictionary     typealias u = usermodel      func mapfromsource(data:nsdictionary) -> usermodel {         var user = usermodel()         var accountsdata:nsarray = data["accounts"] nsarray         // swift 1.2, need line instead         // var accountsdata:nsarray = data["accounts"] as! nsarray         return user     } }