Why Swift is designed for safety and speed in iOS Swift - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a constant in Swift.

iOS Swift

let [1] = 10

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

Avar

Bconst

Clet

Dfinal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'var' instead of 'let' for constants.

In Swift, let declares a constant, which cannot be changed after assignment. This helps with safety by preventing accidental changes.

2fill in blank

medium

Complete the code to safely unwrap an optional in Swift.

iOS Swift

if let value = [1] {
  print(value)
}

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

Avalue

Bvar

Cnil

DoptionalValue

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to unwrap a non-optional or using 'nil' directly.

Using if let with an optional variable (like optionalValue) safely unwraps it if it contains a value, preventing runtime errors.

3fill in blank

hard

Fix the error in the code by choosing the correct type for the variable.

iOS Swift

var name: [1] = "Swift"

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

AInt

BString

CDouble

DBool

Attempts:

3 left

💡 Hint

Common Mistakes

Using numeric or boolean types for text variables.

The variable name holds text, so its type must be String for the code to work correctly.

4fill in blank

hard

Fill both blanks to create a function that returns the sum of two integers.

iOS Swift

func add(a: Int, b: Int) -> [1] {
  return a [2] b
}

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

AInt

B+

C-

DString

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction instead of addition.

Returning a wrong type.

The function returns an Int and adds two integers using the + operator.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that filters keys with values greater than 5.

iOS Swift

let filtered = dictionary.filter { [1], [2] in [3] > 5 }

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

Akey

Bvalue

Ddict

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong parameter names or filtering by key instead of value.

The filter method uses a closure with key and value parameters, and filters where value is greater than 5.