Closure expression syntax in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a closure that adds two numbers.

Swift

let add = { (a: Int, b: Int) -> Int in return a [1] b }

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

A/

B-

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' will subtract instead of add.

The closure adds two integers using the + operator.

2fill in blank

medium

Complete the code to call the closure with arguments 3 and 5.

Swift

let result = add([1], 5)

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

A4

B3

C5

D6

Attempts:

3 left

💡 Hint

Common Mistakes

Passing 4 or 6 instead of 3 will change the result.

The closure is called with 3 and 5 as arguments, so the first argument is 3.

3fill in blank

hard

Fix the error in the closure syntax to correctly multiply two numbers.

Swift

let multiply = { (a: Int, b: Int) -> Int [1] a * b }

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

Afunc

B->

Cin

Dreturn

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'return' or 'func' instead of 'in' causes syntax errors.

The keyword 'in' separates the closure parameters and return type from the body.

4fill in blank

hard

Fill both blanks to create a closure that returns the square of a number.

Swift

let square = { (num: Int) [1] num [2] num }

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

Ain

B**

C*

Dreturn

Attempts:

3 left

💡 Hint

Common Mistakes

Using '**' for exponentiation is not valid in Swift.

The closure uses 'in' to separate parameters from the body and '*' to multiply the number by itself.

5fill in blank

hard

Fill all three blanks to create a closure that filters even numbers from an array.

Swift

let evens = numbers.filter { [1] in [2] % 2 [3] 0 }

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

Anum

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '==' will filter odd numbers instead.

The closure takes 'num' as input, then checks if 'num % 2 == 0' to filter even numbers.