Learning Swift™ Programming

Generics for Protocols

Protocols can create/define generic types called associated types. You may sometimes want to create a protocol that uses some type that will be decided when you create the object. Earlier in the chapter, you created a List that has a couple of nifty methods and properties. Now you will create a protocol to describe some of the functionality. So here you’ll create a Bucket protocol to describe the adding functionality to the List, so that you can add as many elements as you want—and remove them. You’ll also make a Uniquable protocol, which describes the deDup functionality. Here are the two protocols and their implementation declaration in the List:

Click here to view code image

protocol Bucket {    typealias SomeItem    var ...