Protocol-oriented architecture in iOS Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is protocol-oriented architecture in Swift?

It is a design approach that uses protocols to define blueprints of methods and properties. Types then conform to these protocols to share behavior, promoting code reuse and flexibility.

intermediate

How does protocol-oriented architecture differ from class inheritance?

Instead of inheriting from a base class, types conform to protocols. This avoids tight coupling and allows multiple behaviors to be combined, unlike single inheritance.

intermediate

What is a protocol extension in Swift?

A protocol extension adds default method or property implementations to a protocol, so conforming types get this behavior automatically unless they override it.

intermediate

Why is protocol-oriented architecture beneficial for testing?

Protocols allow you to create mock or stub types easily by conforming to the protocol, enabling isolated and flexible unit testing.

beginner

Give an example of a simple protocol in Swift.

Example:

protocol Drivable {
  func drive()
}

Any type that conforms to Drivable must implement the drive() method.

What keyword defines a protocol in Swift?

A struct

B interface

C class

D protocol

Swift uses the keyword protocol to define protocols.

Which of these is a benefit of protocol-oriented architecture?

A Prevents code reuse

B Forces all types to inherit from a base class

C Allows multiple inheritance of behavior

D Requires use of classes only

Protocols let types adopt multiple behaviors, similar to multiple inheritance.

What feature lets you provide default implementations in protocols?

A Protocol extensions

B Class inheritance

C Structs

D Enums

Protocol extensions allow default method implementations.

Which type can conform to a protocol in Swift?

A Class

B All of the above

C Enum

D Struct

Classes, structs, and enums can all conform to protocols.

Why is protocol-oriented architecture good for testing?

A It allows creating mock types easily

B It makes testing impossible

C It requires inheritance

D It hides all methods

Protocols let you create mock implementations for testing.

Explain protocol-oriented architecture and how it improves code flexibility in Swift.

Think about how protocols define behavior and how types adopt them.

Describe how protocol extensions work and why they are useful.

Consider how you can add methods to protocols themselves.