Generic type declaration in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a generic type declaration in Swift?

A generic type declaration lets you write flexible, reusable functions and types that can work with any type, instead of a specific one.

beginner

How do you declare a generic function in Swift?

You add a placeholder type inside angle brackets after the function name, like <T>, and use T as a type inside the function.

intermediate

Example: What does this Swift code do?
func swapValues<T>(a: inout T, b: inout T) { let temp = a; a = b; b = temp }

This function swaps the values of two variables of any type T. It uses generics so it works with Int, String, or any other type.

intermediate

How do you declare a generic type (like a class or struct) in Swift?

You add a placeholder type inside angle brackets after the type name, for example struct Box<T> { var value: T }.

beginner

Why use generic type declarations instead of specific types?

Generics let you write code once and use it with many types, making your code reusable, safer, and easier to maintain.

What symbol is used to declare a generic type placeholder in Swift?

A []

B {}

C ()

D <>

Generic placeholders are declared inside angle brackets <> in Swift.

Which keyword is used to declare a generic function in Swift?

A func

B generic func

C func<T>

D func with <T>

You declare a generic function by adding after the function name, like func swapValues(...).

What does the generic type T represent in Swift?

A A placeholder for any type

B A specific type called T

C A variable name

D A function name

T is a placeholder that can represent any type when the function or type is used.

Which of these is a correct generic struct declaration in Swift?

A struct Box<T> = { var value: T }

B struct Box<T> { var value: T }

C struct Box<T> (var value: T)

D struct Box { var value: T }

The correct syntax uses angle brackets after the struct name and curly braces for the body.

Why are generics useful in Swift?

A They make code run faster

B They replace all functions

C They allow writing reusable and type-safe code

D They are only for classes

Generics help write reusable code that works with any type safely.

Explain how to declare and use a generic function in Swift.

Think about how you write <T> after the function name and use T as a type.

Describe the benefits of using generic type declarations in Swift programming.

Why would you want one function or type to work with many types?