Swift — Switch

Basic switch

let day = "Monday"

switch day {
case "Monday":
    print("Start of week")
case "Friday":
    print("Almost weekend")
case "Saturday", "Sunday":
    print("Weekend!")
default:
    print("Midweek")
}

Range matching

let score = 85

switch score {
case 90...100:
    print("A")
case 80..<90:
    print("B")
case 70..<80:
    print("C")
default:
    print("F")
}

Tuple matching

let point = (1, 1)

switch point {
case (0, 0):
    print("Origin")
case (_, 0):
    print("On x-axis")
case (0, _):
    print("On y-axis")
case (-2...2, -2...2):
    print("Inside 2x2 box")
default:
    print("Outside")
}

Value binding

let anotherPoint = (2, -2)

switch anotherPoint {
case let (x, y) where x == y:
    print("On line x == y")
case let (x, y) where x == -y:
    print("On line x == -y")
case let (x, y):
    print("Somewhere else at (\(x), \(y))")
}

where clause

let temperature = 35

switch temperature {
case 0...10:
    print("Cold")
case 11...25:
    print("Mild")
case 26...35 where temperature > 30:
    print("Very hot")
default:
    print("Hot")
}

Enum matching

enum HttpStatus: Int {
    case ok = 200
    case notFound = 404
    case serverError = 500
}

let status = HttpStatus.notFound

switch status {
case .ok:
    print("Success")
case .notFound:
    print("Not found")
case .serverError:
    print("Server error")
}

Exhaustive checking

// Swift requires exhaustive switching
// Missing cases cause compile error

enum Coin { case heads, tails }

let coin = Coin.heads

switch coin {
case .heads:
    print("Heads")
case .tails:
    print("Tails")
// All cases covered - no default needed
}

Mini Practice

Write Swift code that:

1. Uses switch with ranges and tuples
2. Adds a where clause to a switch case
3. Pattern matches an enum
4. Demonstrates exhaustive switching

Up Next

In the next lesson, you'll learn about Loops — for, while, and iteration in Swift.