Swift 4 Protocol-Oriented Programming - Third Edition

Defining a protocol

The syntax we use to define a protocol is very similar to the syntax used to define a class, structure, or enumeration. The following example shows the syntax used to define a protocol:

Protocol MyProtocol { 
  //protocol definition here 
} 

To define the protocol, we use the protocol keyword followed by the name of the protocol. We then put the requirements, which our protocol defines, between curly brackets. Custom types can state that they conform to a particular protocol by placing the name of the protocol after the type's name, separated by a colon. The following example shows how we would define that a structure conforms to a protocol:

struct MyStruct: MyProtocol { 
  //structure implementation here 
} 

A type can also conform ...