Protocol inheritance in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is protocol inheritance in Swift?

Protocol inheritance means one protocol can require all the properties and methods of another protocol. It lets you build new protocols based on existing ones, like stacking rules.

beginner

How do you declare a protocol that inherits from another protocol in Swift?

You write the new protocol name followed by a colon and the name of the protocol it inherits from. Example: protocol B: A { } means B inherits from A.

intermediate

Can a protocol inherit from multiple protocols in Swift?

Yes, a protocol can inherit from more than one protocol by listing them separated by commas. Example: protocol C: A, B { } means C inherits from both A and B.

intermediate

What happens if a protocol inherits from another protocol with required properties or methods?

The inheriting protocol also requires those properties or methods. Any type adopting the new protocol must implement all requirements from both protocols.

beginner

Why use protocol inheritance instead of just one big protocol?

Protocol inheritance helps keep code organized and flexible. You can build small, focused protocols and combine them as needed, making your code easier to understand and reuse.

How do you declare a protocol B that inherits from protocol A in Swift?

A protocol B: A { }

B protocol B inherits A { }

C protocol B extends A { }

D protocol B -> A { }

In Swift, protocol inheritance uses a colon ':' to specify the parent protocol.

Can a Swift protocol inherit from multiple protocols?

A Yes, by listing protocols separated by commas

B Yes, but only two protocols max

C No, only one protocol can be inherited

D No, protocols cannot inherit

Swift allows multiple protocol inheritance by listing protocols separated by commas.

If protocol B inherits from protocol A, what must a type conforming to B do?

A Implement only B's requirements

B No implementation needed

C Implement only A's requirements

D Implement requirements of both A and B

A type conforming to B must satisfy all requirements from both B and A.

Why is protocol inheritance useful?

A To avoid writing any code

B To create one big protocol with all features

C To organize and combine small protocols flexibly

D To make protocols slower

Protocol inheritance helps organize code by combining small, focused protocols.

Which keyword is used to declare a protocol in Swift?

A struct

B protocol

C class

D interface

The keyword protocol is used to declare protocols in Swift.

Explain how protocol inheritance works in Swift and why it is useful.

Think about how one protocol can build on another and how that helps keep code clean.

Describe what a type must do when it conforms to a protocol that inherits from other protocols.

Remember that inherited protocols add to the list of rules a type must follow.