Enum declaration and cases in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an enum in Swift?

An enum (short for enumeration) is a way to group related values under a common type. It helps organize options or choices in your code.

beginner

How do you declare an enum with cases in Swift?

Use the enum keyword, then list cases inside curly braces. For example:<br>

enum Direction {
  case north
  case south
  case east
  case west
}

intermediate

Can enum cases have associated values in Swift?

Yes! Enum cases can store extra information called associated values. For example:<br>

enum Barcode {
  case upc(Int, Int, Int, Int)
  case qrCode(String)
}

beginner

How do you use an enum case in Swift code?

You create a value by writing the enum name, a dot, then the case name. For example:<br><pre>let direction = Direction.north</pre>

beginner

What is the benefit of using enums instead of strings or numbers for fixed options?

Enums make your code safer and clearer. They prevent mistakes like typos and make it easy to see all possible options in one place.

How do you declare an enum named Color with cases red, green, and blue in Swift?

A enum Color { case red, green, blue }

B class Color { var red, green, blue }

C struct Color { let red, green, blue }

D enum Color = [red, green, blue]

Option A correctly declares an enum with three cases using the enum keyword and case syntax.

Which of these is a valid way to create a value of enum Direction with case east?

A let d = Direction->east

B let d = Direction.east

C let d = Direction[east]

D let d = Direction.east()

You create enum values by writing the enum name, a dot, then the case name without parentheses.

Can enum cases in Swift have extra data attached?

A Only if declared as classes

B No, enums only hold fixed names

C Yes, but only strings

D Yes, using associated values

Swift enums can have associated values of any type attached to cases.

What keyword starts an enum declaration in Swift?

A enum

B class

C struct

D case

The enum keyword is used to declare an enumeration.

Why use enums instead of strings for fixed options?

A Because enums use less memory

B Because strings are slower

C To avoid typos and improve code clarity

D Because strings cannot be compared

Enums help prevent mistakes like typos and make code easier to understand.

Explain how to declare an enum with multiple cases in Swift and how to create a value from it.

Think about the basic syntax and how you pick a case.

Describe what associated values are in Swift enums and give an example.

Imagine a case that holds more than just a name.