iOS Development Swift Programming Language

Question 1

What keyword is used in Swift to declare a constant?

Accepted Answer

let

Answer

In Swift, `let` declares a constant whose value cannot be changed after it is set.

Question 2

Which Swift feature allows a variable to hold either a value or nil?

Accepted Answer

Optional

Answer

Swift Optionals allow a variable to represent either a wrapped value or the absence of a value (nil).

Question 3

What does the `guard` statement do in Swift?

Accepted Answer

Exits the current scope if a condition is false

Answer

`guard` evaluates a condition and requires early exit from the current scope if the condition is false.

Question 4

Which Swift collection type stores key-value pairs?

Accepted Answer

Dictionary

Answer

A Swift Dictionary stores associations between keys of one type and values of another type.

Question 5

What is a Swift closure?

Accepted Answer

A self-contained block of functionality that can be passed around

Answer

Closures are self-contained blocks of code that can capture and store references to variables from their surrounding context.

iOS Development Practice Test