Collection mutability tied to let/var in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a mutable array.

Swift

var numbers = [1]

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

A[1, 2, 3]

Blet [1, 2, 3]

C(1, 2, 3)

Dvar (1, 2, 3)

Attempts:

3 left

💡 Hint

Common Mistakes

Using let instead of var makes the array immutable.

Using parentheses instead of square brackets for arrays.

Using var with an array literal [1, 2, 3] creates a mutable array.

2fill in blank

medium

Complete the code to add an element to a mutable array.

Swift

var fruits = ["apple", "banana"]
fruits.[1]("orange")

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

Aremove

Binsert

Cappend

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using remove or pop which remove elements.

Using insert without specifying an index.

The append method adds a new element to the end of a mutable array.

3fill in blank

hard

Fix the error in the code to modify an immutable array.

Swift

[1] colors = ["red", "green", "blue"]
colors.append("yellow")

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

Avar

Blet

Cconst

Dfinal

Attempts:

3 left

💡 Hint

Common Mistakes

Using let which makes the array immutable.

Using keywords from other languages like const or final.

You cannot modify an array declared with let. To fix the error, declare the array with var instead of let.

4fill in blank

hard

Fill both blanks to create a mutable dictionary and add a new key-value pair.

Swift

var capitals = [1]
capitals["France"] = [2]

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

A["USA": "Washington"]

B"Paris"

C"London"

Dlet ["USA": "Washington"]

Attempts:

3 left

💡 Hint

Common Mistakes

Using let instead of var for mutable collections.

Using parentheses instead of square brackets for dictionaries.

Use var with a dictionary literal to create a mutable dictionary. Then assign a new value to a key to add it.

5fill in blank

hard

Fill all three blanks to declare an immutable set and check if it contains a value.

Swift

let primes: Set<Int> = [1]
let containsFive = primes.[2](5)
print(containsFive)  // [3]

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

A[2, 3, 5, 7]

Bcontains

Ctrue

Dvar

Attempts:

3 left

💡 Hint

Common Mistakes

Declaring the set with var instead of let.

Using incorrect methods like containsValue.

Expecting false when the value is actually in the set.

Use a set literal with square brackets to declare the set. Use the contains method to check membership. The result is true because 5 is in the set.