Optionals and unwrapping in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an optional String variable named name.

iOS Swift

var name: [1]

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

AOptional

BString

CString?

DOptional<String>

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the question mark and declaring it as a normal String.

Using the word Optional without the generic type.

In Swift, to declare an optional String, you add a question mark after the type: String?.

2fill in blank

medium

Complete the code to safely unwrap the optional variable name using if let.

iOS Swift

if let unwrappedName = [1] {
  print("Hello, \(unwrappedName)!")
}

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

AunwrappedName

Bname

Cname!

DOptional(name)

Attempts:

3 left

💡 Hint

Common Mistakes

Using the unwrapped variable name inside the if let condition.

Forcing unwrap with exclamation mark instead of safe unwrapping.

Use if let followed by the optional variable to unwrap it safely.

3fill in blank

hard

Fix the error in force unwrapping the optional age variable.

iOS Swift

let age: Int? = 25
let unwrappedAge = [1]

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

Aage!

Bage

COptional(age)

Dage?

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the exclamation mark and causing a type mismatch.

Using optional chaining instead of force unwrapping.

To force unwrap an optional, use the exclamation mark after the variable name.

4fill in blank

hard

Fill both blanks to unwrap optional email and provide a default value if nil.

iOS Swift

let email: String? = nil
let userEmail = [1] ?? [2]

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

Aemail

B"[e-mail]"

Cemail!

Dnil

Attempts:

3 left

💡 Hint

Common Mistakes

Using force unwrap instead of nil-coalescing operator.

Providing nil as the default value.

The nil-coalescing operator ?? unwraps the optional or uses the default value if nil.

5fill in blank

hard

Fill all three blanks to unwrap optional number safely and multiply by 2.

iOS Swift

let number: Int? = 10
if let [1] = [2] {
  let result = [3] * 2
  print(result)
}

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

AsafeNumber

Bnumber

Dnumber!

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same variable name for unwrapped and optional variables.

Forcing unwrap inside if let instead of safe unwrapping.

Use if let to unwrap number into safeNumber and then multiply.