Protocol requirements (methods and properties) in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a protocol in Swift?

A protocol in Swift is like a blueprint that defines methods and properties a type must have. It tells what to do, but not how to do it.

beginner

Can protocols require both methods and properties?

Yes, protocols can require methods (functions) and properties (variables) that conforming types must implement.

intermediate

What does it mean when a protocol property is declared with { get set }?

It means the property must be readable and writable by the conforming type.

beginner

How do you declare a method requirement in a Swift protocol?

You write the method signature without a body inside the protocol. For example: <br>func start()

intermediate

Can protocol requirements specify if a property is a variable or constant?

No, protocols only specify if a property is gettable or settable. The conforming type decides if it uses var or let.

What must a type do when it conforms to a protocol with property requirements?

A Ignore property requirements

B Only implement methods, properties are optional

C Implement all required properties with correct get/set access

D Implement properties but methods are optional

A type must implement all required properties with the correct get/set access as specified by the protocol.

How do you declare a read-only property requirement in a protocol?

A var name: String { set }

B var name: String { get }

C let name: String

D func name() -> String

Using { get } means the property must be readable but not necessarily writable.

Which of these is a valid method requirement in a Swift protocol?

A func run()

B func run() {}

C func run() -> Void {}

D func run() -> Void { print("Run") }

Protocol method requirements only declare the signature without a body.

If a protocol requires a property with { get set }, can a conforming type implement it as a constant (let)?

A Only if the property is static

B Yes, constants are allowed

C Only if the property is private

D No, it must be a variable (var) to allow setting

Properties with { get set } must be writable, so they cannot be constants.

What happens if a type does not implement all protocol requirements?

A Compilation error

B The program runs but with warnings

C The missing requirements are ignored

D The protocol is automatically changed

Swift requires all protocol requirements to be implemented; otherwise, it causes a compilation error.

Explain what protocol requirements are in Swift and how they apply to methods and properties.

Think about what a protocol asks a type to provide.

Describe the difference between { get } and { get set } in protocol property requirements.

Focus on property access levels.