Enum declaration and cases in Swift - Step-by-Step Execution

Concept Flow - Enum declaration and cases

Start

↓

Declare enum with cases

↓

Create variable of enum type

↓

Assign one of the enum cases

↓

Use enum variable in code

↓

End

This flow shows how to declare an enum, create a variable of that enum type, assign a case, and then use it.

Execution Sample

Swift

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

var currentDirection = Direction.north

Declares an enum Direction with four cases and assigns the north case to a variable.

Execution Table

Step	Action	Code Line	Variable	Value	Notes
1	Declare enum Direction with cases north, south, east, west	enum Direction {...}	-	-	Enum type created
2	Create variable currentDirection of type Direction	var currentDirection = Direction.north	currentDirection	Direction.north	Variable assigned enum case north
3	Use currentDirection in code (example: print)	print(currentDirection)	currentDirection	north	Outputs 'north' when printed

💡 All enum cases declared and variable assigned successfully

Variable Tracker

Variable	Start	After Step 2	After Step 3
currentDirection	undefined	Direction.north	Direction.north

Key Moments - 2 Insights

Why do we write Direction.north instead of just north when assigning?

Because north is a case inside the Direction enum, we must specify the enum type to avoid confusion. See execution_table step 2 where currentDirection is assigned Direction.north.

Can we assign a value to an enum case directly?

No, enum cases are fixed identifiers. You assign the case itself, not a separate value. This is shown in execution_table step 2 where currentDirection gets assigned the case Direction.north.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of currentDirection after step 2?

A Direction.south

B undefined

C Direction.north

D north

💡 Hint

Check the 'Value' column in execution_table row for step 2.

At which step is the enum Direction declared?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Look at the 'Action' column in execution_table for the declaration.

If we change currentDirection to Direction.west at step 2, what will be printed at step 3?

A Direction.west

B west

C north

D undefined

💡 Hint

The variable value changes at step 2 and is printed at step 3, see variable_tracker.

Concept Snapshot

enum EnumName {
  case case1
  case case2
  ...
}

Use with: var v = EnumName.case1
Enum cases are fixed named values grouped under one type.

Full Transcript

This example shows how to declare an enum named Direction with four cases: north, south, east, and west. Then, a variable currentDirection is created and assigned the case Direction.north. The execution table traces the steps: first the enum is declared, then the variable is assigned, and finally the variable is used (for example, printed). The variable tracker shows currentDirection starts undefined and becomes Direction.north after assignment. Key moments clarify why we use Direction.north instead of just north and that enum cases are fixed identifiers. The quiz questions test understanding of variable values at each step and the enum declaration step.