What is Swift - Practice Questions & Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is Swift primarily used for?

Swift is a programming language created by Apple. What is its main use?

A Building iOS, macOS, watchOS, and tvOS apps

B Creating Android applications

C Developing Windows desktop software

D Writing server-side scripts only

💡 Hint

Think about which devices Apple makes and what language they promote for app development.

Swift is designed by Apple to build apps for their platforms like iPhone, Mac, Apple Watch, and Apple TV.

❓ Predict Output

intermediate

What is the output of this Swift code?

Look at this Swift code and choose the output it produces.

Swift

let greeting = "Hello"
let name = "Sam"
print("\(greeting), \(name)!")

A Error: Cannot print variables this way

B greeting, name!

C Hello, Sam!

D Hello name!

💡 Hint

Check how variables are inserted inside strings in Swift.

Using \(variable) inside a string inserts the variable's value. So it prints 'Hello, Sam!'.

❓ Predict Output

advanced

What does this Swift code print?

Analyze the code and select the output it produces.

Swift

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

A Error: map function not found

B [1, 2, 3, 4, 5]

C [1, 4, 9, 16, 25]

D [2, 4, 6, 8, 10]

💡 Hint

Remember that map applies a function to each item in the array.

The map function multiplies each number by 2, so the output is [2, 4, 6, 8, 10].

🔧 Debug

advanced

What error does this Swift code raise?

Find the error in this Swift code snippet.

Swift

let number: Int = "123"
print(number)

A Type mismatch error

B Syntax error: missing semicolon

C No error, prints 123

D Runtime error: nil value

💡 Hint

Check if the type on the left matches the value on the right.

You cannot assign a String value to an Int variable directly in Swift. This causes a type mismatch error.

🧠 Conceptual

expert

Which feature makes Swift safe and fast?

Swift is known for safety and speed. Which feature helps achieve this?

A Using dynamic typing for flexibility

B Optionals to handle absence of values safely

C Manual memory management like in C

D No type checking at compile time

💡 Hint

Think about how Swift avoids crashes from missing values.

Optionals let Swift safely handle missing or nil values, preventing many common errors and improving safety.