Protocol composition lets our types adopt multiple protocols. This is a major advantage that we get when we use protocols rather than a class hierarchy because classes, in Swift and other single-inheritance languages, can only inherit from one superclass. The syntax for protocol composition is the same as the protocol inheritance that we just saw. The following example shows how to do protocol composition:

struct MyStruct: ProtocolOne, ProtocolTwo, Protocolthree { 
    // implementation here 
} 

Protocol composition allows us to break our requirements into many smaller components rather than inheriting all requirements from a single superclass or class hierarchy. This allows our type families to grow in width rather than height, which means we avoid creating bloated types that contain requirements that are not needed. Protocol composition may seem like a very simple concept, but it is a concept that is essential to protocol-oriented programming. Let's look...