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41 interview questions on Swiftfor developers (2025)

Test your technical skills before an interview of Swift with 41 corrected questions. Beginner, Intermediate or Expert level.

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41 questions
Hard
2 votes425 runs
1 comment

How to check if a variable is defined in Swift

Mobile developer
swift
optionals
Jorge Gomesat Nov 27, 2021
Hard
1 vote430 runs0 comment

What is the purpose of the required keyword in Swift?

Mobile developer
swift
constructor
Smart&Softat Nov 5, 2021
Hard
1 vote417 runs0 comment

Use dispatch_once from Grand Central Dispatch,Declare the portion of code whose result is stored in a static let in Swift.

Mobile developer
dispatch_once
static let
Smart&Softat Nov 16, 2021
Hard
1 vote415 runs0 comment

What are the 3 reasons to use weak var monProtocol: PokemonDelegate?

Mobile developer
protocol
struct
class
Smart&Softat Nov 27, 2021
Easy
1 vote411 runs0 comment

Swift: What is the output of the following code? `var x = 10; x = x + undefined; print(x)`

Mobile developer
optional
Smart&Softat Nov 27, 2021
Easy
1 vote402 runs0 comment

Is the following code valid? ``` var x = 10 var y = x ```

Mobile developer
swift
Smart&Softat Nov 27, 2021
Easy
0 vote470 runs0 comment

Is the following a valid Swift variable name? 'undefined'

Mobile developer
swift
Smart&Softat Apr 12, 2023
Medium
0 vote438 runs0 comment

How to use the `switch` statement in Swift

Mobile developer
swift
optionals
Smart&Softat Nov 27, 2021
Medium
0 vote436 runs0 comment

Automatic retain and release markers during compilation, freeing manual memory management

Mobile developer
memory management
swift
Smart&Softat Nov 27, 2021
Medium
0 vote432 runs0 comment

How to use the `switch` statement in Swift

Mobile developer
swift
optionals
Smart&Softat Nov 27, 2021
Easy
0 vote425 runs0 comment

How to make a property editable in InterfaceBuilder

Mobile developer
swift
interface builder
Smart&Softat Nov 27, 2021
Expert
0 vote423 runs
1 comment

What is the type of an undefined variable in Swift?

Mobile developer
types
Smart&Softat Nov 3, 2021
Medium
0 vote420 runs0 comment

How to use the internal notification center in Swift

Mobile developer
swift
error
Smart&Softat Nov 16, 2021
Medium
0 vote414 runs0 comment

Swift: What is the difference between unowned and weak?

Mobile developer
swift
unowned
Smart&Softat Nov 27, 2021
Hard
0 vote412 runs0 comment

Write a Swift function that takes a closure as a parameter and returns the result of the closure.

Mobile developer
closures
parameters
Smart&Softat Nov 27, 2021
Medium
0 vote411 runs0 comment

How to use the `switch` statement in Swift

Mobile developer
swift
optionals
Smart&Softat Nov 27, 2021
Easy
0 vote410 runs0 comment

Explain the difference between frame and bounds in SwiftUI.

Mobile developer
swift
frame
bounds
Smart&Softat Nov 27, 2021
Medium
0 vote410 runs0 comment

A weak reference does not increase the retain count of an object

Mobile developer
swift
references
Smart&Softat Nov 27, 2021
Easy
0 vote409 runs0 comment

Write a Swift function that takes an array of strings and returns a new array with the strings in reverse order.

Mobile developer
array
functions
Smart&Softat Nov 27, 2021
Medium
0 vote408 runs0 comment

Return the size of each item from UICollectionViewFlowLayoutDelegate, Simply add an estimatedSize to the UICollectionView

Mobile developer
swift
collectionview
Smart&Softat Nov 27, 2021
Swift tests