Cocoa Programming for OS X: The Big Nerd Ranch Guide

For the More Curious: Creating a Protocol

Creating your own protocol is very simple. Here is a protocol with two methods.

p​r​o​t​o​c​o​l​ ​E​n​c​r​y​p​t​a​b​l​e​ ​{​
 ​ ​ ​ ​i​n​i​t​(​e​n​c​r​y​p​t​e​d​D​a​t​a​:​ ​N​S​D​a​t​a​)​
 ​ ​ ​ ​f​u​n​c​ ​e​n​c​r​y​p​t​(​)​ ​-​>​ ​N​S​D​a​t​a​
}​

The protocol would typically be defined in a file called Encryptable.swift:

If your protocol is tagged @objc, it is possible to add optional methods.

@​o​b​j​c​ ​p​r​o​t​o​c​o​l​ ​E​n​c​r​y​p​t​a​b​l​e​ ​{​
 ​ ​ ​ ​i​n​i​t​(​e​n​c​r​y​p​t​e​d​D​a​t​a​:​ ​N​S​D​a​t​a​)​
 ​ ​ ​ ​f​u​n​c​ ​e​n​c​r​y​p​t​(​)​ ​-​>​ ​N​S​D​a​t​a​

 ​ ​ ​ ​o​p​t​i​o​n​a​l​ ​f​u​n​c​ ​s​c​h​e​m​e​N​a​m​e​(​)​ ​-​>​ ​S​t​r​i​n​g​
}​

In this example, encryptData(_:) and ...