Swift MCQ Practice Test

Q1. What is the primary purpose of string interpolation in Swift?

• A. To insert the current date and time.
• B. To insert the value of a variable into a string. ✓
• C. To access command-line arguments.
• D. To format the output as a string.

Q2. What character is used to escape special characters, such as a double quote, within a Swift string literal?

• A. The '!' character
• B. The '#39; character
• C. The '' character ✓
• D. The '%' character

Q3. What is the purpose of the ".map" function in a Swift array?

• A. It is used to filter elements from an array.
• B. It is used to transform elements in an array. ✓
• C. It is used to sort elements in an array.
• D. It is used to remove elements from an array.

Q4. What is the purpose of the '@discardableResult' attribute in Swift?

• A. To indicate that a function may throw an error
• B. To suppress the return value of a function ✓
• C. To enable a function to be called concurrently
• D. To specify the return type of a function

Q5. What is the purpose of the "'self' keyword in a Swift closure?

• A. To capture the enclosing function's context ✓
• B. To create a new scope for the closure
• C. To pass the closure as an argument to a function
• D. To return a value from the closure

Q6. What is the purpose of the ".self" keyword in Swift?

• A. To create a new instance of the class
• B. To refer to the current type ✓
• C. To call a class method
• D. To access a class property

Q7. What is the purpose of the '!' character when used with an optional in Swift?

• A. To declare an optional variable.
• B. To force unwrap an optional, potentially leading to a runtime error if the optional is nil. ✓
• C. To safely unwrap an optional.
• D. To define a constant.

Q8. What is the purpose of the \\@escaping keyword in a Swift closure?

• A. To indicate that the closure captures self
• B. To specify that the closure should be executed on the main thread
• C. To mark the closure as escaping, allowing it to outlive the function that called it ✓
• D. To enable the use of async/await in the closure

Q9. In Swift, which syntax is used for string interpolation - embedding a value inside a string literal?

• A. \(value) ✓
• B. $value
• C. {value}
• D. #value

Q10. What is the purpose of the "if let" statement in Swift?

• A. To check if a value is true or false
• B. To unwrap an optional value without forcing it ✓
• C. To assign a value to a variable only if it is not nil
• D. To check if a value is equal to another value

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