Understanding Swift Switch Statement

What is a Swift Switch Statement?

A switch statement evaluates an expression against multiple cases and executes the matching block of code. It is an effective alternative to if-else statements when handling multiple conditions.

Key Benefits:

Enhances code readability
More efficient than if-else for multiple conditions
Supports advanced features like pattern matching, value binding, and range matching

Syntax of a Switch Statement

switch expression {
case value1:
// Code to execute
fallthrough // Optional
case value2:
// Code to execute
break // Optional
default:
// Default case if no match
}

Example 1: Basic Switch Statement in Swift

import Foundation

let age = 25

switch age {
case 18:
print("You just became an adult!")
case 21:
print("You can legally drink!")
case 25:
print("You are in your mid-20s!")
default:
print("Age is just a number!")
}

Output

You are in your mid-20s!

Break Statement in Switch

The break statement terminates a switch case execution immediately, preventing code from executing unintentionally.

import Foundation

let day = 3

switch day {
case 1:
print("Monday")
break
case 2:
print("Tuesday")
break
case 3:
print("Wednesday")
break
case 4:
print("Thursday")
break
case 5:
print("Friday")
break
default:
print("Weekend")
}

Output

Wednesday

Fallthrough in Switch Statements

In Swift, switch cases do not fall through by default. If you want execution to continue to the next case, use fallthrough explicitly.

import Foundation

let num = 2

switch num {
case 1:
print("This is case 1")
fallthrough
case 2:
print("This is case 2")
fallthrough
case 3:
print("This is case 3")
default:
print("End of switch block")
}

Output

This is case 2
This is case 3

Using Ranges in Switch Statements

You can check if a value falls within a specific range using Swift’s range operators.

import Foundation

let temperature = 27

switch temperature {
case ..<0:
print("Freezing cold")
case 0...20:
print("Cold")
case 21...30:
print("Moderate")
case 31...:
print("Hot")
default:
print("Invalid temperature")
}

Output

Moderate

Tuple Matching in Switch Statements

Swift allows tuple matching to evaluate multiple values simultaneously.

import Foundation

let coordinates = (x: 5, y: 10)

switch coordinates {
case (0, 0):
print("Origin point")
case (5, 10):
print("Point is at (5,10)")
default:
print("Point is somewhere else")
}

Output

Point is at (5,10)

Value Binding in Switch Statements

Value binding allows you to store case values as temporary variables within the case block.

import Foundation

let number = 17

switch number {
case let x where x % 2 == 0:
print("\(x) is even")
case let y where y % 2 != 0:
print("\(y) is odd")
default:
print("Unknown number")
}

Output

17 is odd

Using the Where Clause in Switch Statements

The where clause filters case conditions with additional requirements. It allows you to add extra checks to a case in a switch statement.

Example

import Foundation

let score = 77

switch score {
case 0...59:
print("Failed")
case 60...79 where score < 75:
print("Passed")
case 60...79 where score >= 75:
print("Passed with distinction")
case 80...100:
print("Excellent result!")
default:
print("Invalid score")
}

Output

Passed with distinction

Compound Cases in Swift Switch Statements

You can group multiple case values together to execute the same block of code. This is useful when multiple cases share the same logic.

Example

import Foundation

let luckyNumber = 7

switch luckyNumber {
case 1, 3, 5, 7, 9:
print("You picked an odd number")
case 2, 4, 6, 8, 10:
print("You picked an even number")
default:
print("Number not in the list")
}

Output

You picked an odd number