Switch statement power in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Switch with tuple pattern matching

What is the output of this Swift code using a switch statement with tuple pattern matching?

Swift

let point = (2, -2)
switch point {
case (let x, let y) where x == y:
    print("On the line x == y")
case (let x, let y) where x == -y:
    print("On the line x == -y")
default:
    print("Just a point")
}

A On the line x == y

B Just a point

C Compilation error

D On the line x == -y

💡 Hint

Check the conditions in the where clauses carefully.

The tuple (2, -2) matches the second case because 2 == -(-2) is true, so it prints "On the line x == -y".

❓ Predict Output

intermediate

Switch with value binding and fallthrough

What will be printed when this Swift code runs?

Swift

let number = 3
switch number {
case 1:
    print("One")
case 2, 3:
    print("Two or Three")
    fallthrough
case 4:
    print("Four")
default:
    print("Other")
}

A

Two or Three
Four

B Two or Three

C Four

D Other

💡 Hint

Remember what fallthrough does in Swift switch statements.

The case 3 matches and prints "Two or Three", then fallthrough causes the next case (4) to execute, printing "Four".

🔧 Debug

advanced

Why does this switch cause a compile error?

This Swift code causes a compile error. What is the reason?

Swift

let value = 5
switch value {
case 1..<5:
    print("Less than 5")
case 5:
    print("Equal to 5")
case 6...10:
    print("Between 6 and 10")
default: 
    print("Other")
}

A The case _: syntax is invalid; it should be default.

B The range 1..<5 overlaps with 5 causing ambiguity.

C The switch cases are not exhaustive.

D The case _: is unreachable because previous cases cover all values.

💡 Hint

Check the syntax for the default case in Swift switch statements.

Swift requires the default case to be written as 'default:', not 'case _:'. Using 'case _:' causes a syntax error.

❓ Predict Output

advanced

Switch with multiple patterns and where clause

What is the output of this Swift code?

Swift

let char: Character = "e"
switch char {
case "a", "e", "i", "o", "u" where char.isLowercase:
    print("Lowercase vowel")
case "A", "E", "I", "O", "U":
    print("Uppercase vowel")
default:
    print("Consonant")
}

A Lowercase vowel

B Uppercase vowel

C Compilation error

D Consonant

💡 Hint

Check the placement of the where clause with multiple patterns.

In Swift, a where clause cannot be applied to multiple patterns combined with commas. This causes a compile error.

❓ Predict Output

expert

Switch with enum and associated values

Given this Swift enum and switch, what will be printed?

Swift

enum Result {
    case success(Int)
    case failure(String)
}

let result = Result.success(42)
switch result {
case .success(let code) where code > 40:
    print("Success with code > 40")
case .success:
    print("Success with code <= 40")
case .failure(let message):
    print("Failure: \(message)")
}

A Success with code <= 40

B Success with code > 40

C Failure: 42

D Compilation error

💡 Hint

Look at the associated value and the where clause condition.

The enum case is success with associated value 42, which is greater than 40, so the first case matches and prints "Success with code > 40".