Swift Arrays Quiz

Topic: Swift Arrays

Swift Quiz #05: Swift Arrays

In Swift, an array is a collection type that allows you to store multiple values of the same type in an ordered list

7 mins read

1. What is the output?

 var numbers = [1, 2, 3, 4, 5]
 let transformedNumbers = numbers.map { $0 * 2 }
 print(transformedNumbers)

[2, 4, 6, 8, 10]

[1, 2, 3, 4, 5]

[1, 4, 9, 16, 25]

2. Which method is used to find the first index of a specific element in an array?

index(of:)

findIndex(of:)

firstIndex(of:)

3. What is the output?

 let names = ["Alice", "Bob", "Charlie"]
 let result = names.allSatisfy { $0.count >= 3 }
 print(result)

true

["Alice", "Charlie"]

[true, true, true]

4. What is the output?

 let numbers = [1, 2, 3, 4, 5]
 let result = numbers.reduce(3) { $0 + $1 }
 print(result)

5. Which method can be used to check if an array contains a specific element?

contains(_:)

includes(_:)

has(_:)

6. What is the output?

 let numbers = [1, 2, 3, 4, 5]
 let result = numbers.filter { $0 % 2 == 0 }
               .flatMap { Array(repeating: $0, count: $0) }
 print(result)

[2, 2, 4, 4, 4, 4]

[0, 0, 0, 0, 0, 0]

[[0,0],[0,0,0,0]]

7. What is the output?

 let names = ["Alice", "Bob", "Charlie", "David"]
 let result = names.compactMap { $0.count > 4 ? $0 : nil } 
 print(result)

["Alice", "Bob", "Charlie", "David"]

["Alice", "Charlie", "David"]

["Bob", "David"]

8. What is the difference between map and flatMap when dealing with optionals?

map unwraps optionals, while flatMap keeps the optionals intact.

map transforms optionals, while flatMap unwraps optionals.

There is no difference between map and flatMap when dealing with optionals.

9. What is the output?

 let words = ["Hello", "World", "Swift"]
 let result = words.joined(separator: " ") 
 print(result)

HelloWorldSwift

Hello World Swift

Hello, World, Swift