Syntax Quiz - Languages Swift

Free practice quiz: Syntax (Languages Swift). 50 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which keyword is used to declare a constant in Swift?

   1. var
   2. let
   3. const
   4. constant
   Show answer

   Answer: B. let

   In Swift, the `let` keyword is used to declare a constant, which means its value cannot be changed after it's initially assigned. The `var` keyword is used for variables.

2. How do you declare a property within a struct in Swift?

   1. var propertyName: DataType
   2. let propertyName: DataType
   3. Both var and let propertyName: DataType
   4. define propertyName: DataType
   Show answer

   Answer: C. Both var and let propertyName: DataType

   Properties within a Swift struct can be declared using either the `var` keyword for mutable properties or the `let` keyword for constants.

3. What is the correct way to declare an implicitly unwrapped optional String in Swift?

   1. var name: String?
   2. var name: String!
   3. var name: String
   4. var name: Optional<String>
   Show answer

   Answer: B. var name: String!

   An implicitly unwrapped optional is declared by appending an exclamation mark (`!`) to the type. It's treated like an optional but can be accessed directly without unwrapping, assuming it always has a value.

4. Which syntax is used for accessing a named element in a Swift tuple?

   1. myTuple.0
   2. myTuple.first
   3. myTuple.name
   4. myTuple[0]
   Show answer

   Answer: C. myTuple.name

   If a tuple has named elements, you can access them using dot notation with their names (e.g., `myTuple.name`). Unnamed elements are accessed using their zero-based index (e.g., `myTuple.0`).

5. What is the Swift keyword used to refer to the current instance of a type?

   1. self
   2. this
   3. current
   4. instance
   Show answer

   Answer: A. self

   The `self` keyword is used within an instance method or computed property to refer to the current instance of the type.

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