Guard for early exit pattern in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to use a guard statement that exits early if the number is not positive.

Swift

func checkNumber(_ number: Int) {
    guard [1] else {
        print("Number is not positive")
        return
    }
    print("Number is positive")
}

Drag options to blanks, or click blank then click option'

Anumber > 0

Bnumber == 0

Cnumber < 0

Dnumber >= 0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'number == 0' which allows zero as positive.

Using 'number < 0' which is the opposite condition.

The guard statement checks if the number is greater than zero. If not, it exits early.

2fill in blank

medium

Complete the guard statement to unwrap the optional string safely.

Swift

func greet(_ name: String?) {
    guard let unwrappedName = [1] else {
        print("No name provided")
        return
    }
    print("Hello, \(unwrappedName)!")
}

Drag options to blanks, or click blank then click option'

Aname!

BString(name)

CunwrappedName

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'name!' which force unwraps and can cause a crash.

Using 'unwrappedName' which is the new constant, not the optional.

The guard statement unwraps the optional 'name' safely using 'let'.

3fill in blank

hard

Fix the error in the guard statement to check if the array is not empty.

Swift

func process(items: [Int]) {
    guard [1] else {
        print("No items to process")
        return
    }
    print("Processing \(items.count) items")
}

Drag options to blanks, or click blank then click option'

Aitems.count == 0

Bitems.isEmpty

C!items.isEmpty

Ditems.count > 0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'items.isEmpty' which exits early when array has items.

Using 'items.count == 0' which is true when empty, opposite of needed.

The guard statement should check that the array is NOT empty using '!items.isEmpty'.

4fill in blank

hard

Fill both blanks to unwrap an optional integer and check it is positive.

Swift

func validate(_ value: Int?) {
    guard let number = [1], number [2] 0 else {
        print("Invalid number")
        return
    }
    print("Valid number: \(number)")
}

Drag options to blanks, or click blank then click option'

Avalue

B>

C>=

Dnumber

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' instead of '>' which allows zero as valid.

Using 'number' instead of 'value' to unwrap.

First unwrap the optional 'value' with 'let'. Then check if 'number' is greater than zero.

5fill in blank

hard

Fill all three blanks to unwrap two optionals and check the second is not empty.

Swift

func process(user: String?, email: String?) {
    guard let username = [1], let userEmail = [2], !userEmail.[3] else {
        print("Missing or empty email")
        return
    }
    print("User: \(username), Email: \(userEmail)")
}

Drag options to blanks, or click blank then click option'

Auser

Bemail

CisEmpty

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'count' instead of 'isEmpty' which requires a comparison.

Not unwrapping both optionals before checking.

Unwrap 'user' and 'email' optionals, then check that 'userEmail' is not empty using '!userEmail.isEmpty'.