For-in loop with collections in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to loop through all elements in the array and print each one.

Swift

let fruits = ["Apple", "Banana", "Cherry"]
for [1] in fruits {
    print([1])
}

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

Aindex

Bfruit

Citem

Dfruits

Attempts:

3 left

💡 Hint

Common Mistakes

Using the collection name instead of a variable for each element.

Using a variable name that suggests an index instead of an element.

In a for-in loop, the variable (here fruit) represents each element in the collection.

2fill in blank

medium

Complete the code to loop through the dictionary and print each key and value.

Swift

let ages = ["Alice": 25, "Bob": 30, "Charlie": 35]
for ([1], age) in ages {
    print("\([1]) is \(age) years old")
}

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

Akey

Bage

Cname

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using the value variable name for the key.

Using a variable name that does not represent keys.

When looping through a dictionary, the first variable is the key (here key), and the second is the value.

3fill in blank

hard

Fix the error in the code to correctly loop through the set and print each element.

Swift

let colors: Set = ["Red", "Green", "Blue"]
for [1] in colors {
    print([1])
}

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

Aindex

Bcolors

Ccolor

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using the collection name instead of a single element variable.

Using a variable name that implies an index which sets do not have.

The loop variable should represent each element in the set, so 'color' is correct.

4fill in blank

hard

Fill both blanks to create a dictionary that maps each word to its length if the length is greater than 3 using reduce.

Swift

let words = ["cat", "house", "dog", "elephant"]
let lengths = words.reduce(into: [String: Int]()) { result, [1] in
    if [2] > 3 {
        result[[1]] = [2]
    }
}

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

Aword

Bword.count

Cword.length

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'word.length' which is not valid in Swift.

Using 'count' alone without specifying the variable.

In Swift, to create a dictionary from a collection, use the element as the key and its count as the value.

5fill in blank

hard

Fill all three blanks to create a for-in loop that prints each index and element from the array.

Swift

let animals = ["dog", "cat", "bird"]
for ([1], [2]) in animals.[3]() {
    print("Index \([1]): \([2])")
}

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

Aindex

Belement

Cenumerated

Ditems

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'items()' which is not a valid method.

Swapping index and element variable names.

Use 'enumerated()' to get index and element pairs from an array in Swift.