Enum declaration and cases in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of enum with raw values

What is the output of this Swift code?

Swift

enum Direction: String {
    case north = "N"
    case south = "S"
    case east = "E"
    case west = "W"
}

let dir = Direction.east
print(dir.rawValue)

A "E"

B "east"

C Direction.east

D "East"

💡 Hint

Look at the rawValue property of the enum case.

The enum Direction has raw values of type String. The case east has raw value "E". Printing dir.rawValue outputs "E".

❓ Predict Output

intermediate

Enum with associated values output

What will this Swift code print?

Swift

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

let res = Result.failure("Error")
switch res {
case .success(let code):
    print("Success with code \(code)")
case .failure(let message):
    print("Failed: \(message)")
}

A Failed: failure

B Failed: Error

C Success with code 0

D Success with code Error

💡 Hint

Check which case is assigned to res and what the associated value is.

The enum instance res is .failure with associated value "Error". The switch matches .failure and prints "Failed: Error".

🔧 Debug

advanced

Identify the error in enum declaration

Which option shows the error when compiling this enum declaration?

Swift

enum Color {
    case red
    case green
    case blue
    case yellow = 4
}

A Error: Missing comma between cases

B No error, compiles fine

C Error: Enum cases cannot have assigned integer values without raw type

D Error: Enum cases must be strings

💡 Hint

Check if enum has raw type when assigning values to cases.

In Swift, enum cases can only have assigned raw values if the enum declares a raw type. Here, Color has no raw type but yellow is assigned 4, causing a compile error.

🧠 Conceptual

advanced

Number of cases in enum

Given this enum, how many cases does it have?

Swift

enum Weekday {
    case monday, tuesday, wednesday
    case thursday
    case friday, saturday, sunday
}

A 7

B 5

C 6

D 3

💡 Hint

Count all the cases separated by commas and lines.

The enum Weekday has 7 cases: monday, tuesday, wednesday, thursday, friday, saturday, sunday.

❓ Predict Output

expert

Output of enum with indirect recursive case

What does this Swift code print?

Swift

enum ArithmeticExpression {
    case number(Int)
    indirect case addition(ArithmeticExpression, ArithmeticExpression)
}

let five = ArithmeticExpression.number(5)
let four = ArithmeticExpression.number(4)
let sum = ArithmeticExpression.addition(five, four)

func evaluate(_ expr: ArithmeticExpression) -> Int {
    switch expr {
    case .number(let value):
        return value
    case .addition(let left, let right):
        return evaluate(left) + evaluate(right)
    }
}

print(evaluate(sum))

A 0

B 54

C Error: indirect case not allowed

D 9

💡 Hint

Think about how the recursive evaluation adds the numbers.

The enum uses indirect case to allow recursion. The evaluate function sums the numbers 5 and 4, resulting in 9.