LinkedIn skill assessment answers and questions — Swift

“سريع has emerged as a powerful and intuitive programming language for developing iOS, macOS, and watchOS applications, offering developers a modern and efficient platform for building innovative software. في هذا الدليل الشامل, we’re thrilled to present a series of أسئلة تقييم المهارات و الإجابات specifically tailored for سريع المستخدمين.

Whether you’re a seasoned developer looking to expand your capabilities or a beginner aiming to understand the basics of this powerful language, this resource is designed to help you become proficient in سريع and its applications. Join us as we explore the core concepts of سريع برمجة, including optionals, closures, protocols, و اكثر, empowering you to leverage the full potential of this essential tool for your iOS and macOS projects.”

Q1. What is this code an example of?

let val = (Double)6

A syntax issue
Typecasting
Assignment
Initialization

مرجع: The Swift Programming Language: Language Guide: أساسيات: Constants and Variables

Q2. What is the error in this code?

let x = 5
guard x == 5 { return }

ال guard is missing the else
Nothing is wrong
ال guard is missing a then
The comparison is wrong

مرجع: The Swift Programming Language: Language Guide: تدفق التحكم: Early Exit

Q3. What is the raw/underlying type of this enum?

enum Direction {
  case north, south, east, west
}

There is none
String
Any
Int

مرجع: The Swift Programming Language: Language Guide: Enumerations: Raw Values

Q4. Why is dispatchGroup used in certain situations?

It allows multiple synchronous or asynchronous operations to run on different queues.
It allows track and control execution of multiple operations together.
It allows operations to wait for each other as desired.
All of these answers.

مرجع: Apple Developer: كابل بيانات: Dispatch: Dispatch Group

Q5. What is this code an example of?

let val = 5
print("value is: \(val)")

String interpolation
String compilation
Method chaining
تسلسل السلسلة

مرجع: The Swift Programming Language: Language Guide: Strings and Characters: String Interpolation

Q6. What are the contents of `vals` after this code is executed?

var vals = [10, 2]
vals.sort { (s1, s2) -> Bool in
  s1 > s2
}

[10, 2]
[2, 10]
nil
This code contains an error

مرجع: Apple Developer: Documentations: سريع: مجموعة مصفوفة: نوع()

Q7. What does this code print?

typealias Thing = [String: Any]
var stuff: Thing
print(type(of: stuff))

Dictionary<String, Any>
Dictionary
Error
Thing

مرجع: The Swift Programming Language: Language Reference: أنواع: Type Identifier

Q8. What is the value of y?

let x = ["1", "2"].dropFirst()
let y = x[0]

This code contains an error
1
2
nil

explanation
dropFirst() من عند Swift.Collection.Array returns a type of ArraySlice<Element>
as in the documentation pages:
@inlinable public func dropFirst(_ k: Int = 1) -> ArraySlice<Element>

The ArraySlice type makes it fast and efficient for you to perform operations on sections of a larger array. Instead of copying over the elements of a slice to new storage, an ArraySlice instance presents a view onto the storage of a larger array. And because ArraySlice presents the same interface as Array, you can generally perform the same operations on a slice as you could on the original array.

Slices Maintain Indices
Unlike Array and ContiguousArray, the starting index for an ArraySlice instance isn’t always zero. Slices maintain the same indices of the larger array for the same elements, so the starting index of a slice depends on how it was created, letting you perform index-based operations on either a full array or a slice.
The above code returns a slice of value ["2"] but the index did not change. let y = x[1] would give the expected result.
To safely reference the starting and ending indices of a slice, always use the startIndex and endIndex properties instead of specific values.
مرجع

Q9. What is the value of test in this code?

var test = 1 == 1

true
YES
1
This code contains an error

مرجع: The Swift Programming Language: Language Guide: Basic Operators: Comparison Operators

Q10. What is the value of y?

var x: Int?
let y = x ?? 5

5
0
nil
This code contains an error

مرجع: The Swift Programming Language: Language Guide: Basic Operators: Nil-Coalescing Operators

سوف تحتاج إلى تحقيق ما لا يقل عن. What is the type of this function?

func add(a: Int, b: Int) -> Int { return a+b }

Int
(Int, Int) -> Int
Int<Optional>
Functions don’t have types.

مرجع: The Swift Programming Language: Language Guide: المهام: Function Types

س 12. What is the correct way to call this function?

func myFunc(_ a: Int, b: Int) -> Int {
  return a + b
}

myFunc(5, b: 6)
myFunc(5, 6)
myFunc(a: 5, b: 6)
myFunc(a, b)

مرجع: The Swift Programming Language: Language Guide: المهام: Function Argument Labels and Parameter Names

Q13. The Codable protocol is _?

A combination of Encodable و Decodable
Not a true protocol
Required of all classes
Automatically included in all classes

المراجع:

س 14. What is the type of value1 in this code?

let value1 = "\("test".count)"

String
Int
null
test.count

مرجع: The Swift Programming Language: Language Guide: Strings and Characters: String Interpolation

س 15. When a function takes a closure as a parameter, when do you want to mark is as escaping?

When it’s executed after the function returns
When it’s scope is undefined
When it’s lazy loaded
All of these answers

مرجع: The Swift Programming Language: Language Guide: Closures: Escaping Closures

س 16. What’s wrong with this code?

class Person {
  var name: String
  var address: String
}

Person has no initializers.
Person has no base class.
var name is not formatted correctly.
address is a keyword.

مرجع: The Swift Programming Language: Language Guide: Initialization: Class Inheritance and Initialization

Q17. What is the value of names after this code is executed?

let names = ["Bear", "Joe", "Clark"]
names.map { (s) -> String in
  return s.uppercased()
}

["BEAR", "JOE", "CLARK"]
["B", "J", "C"]
["Bear", "Joe", "Clark"]
This code contains an error.

س 18. What describes this line of code?

let val = 5

A constant named val of type Int
A variable named val of type item
A constant named val of type Number
A variable named val of type Int

مرجع: The Swift Programming Language: Language Guide: أساسيات: Type Safety and Type Inference

Q19. What is the error in this code?

extension String {
  var firstLetter: Character = "c" {
    didSet {
      print("new value")
    }
  }
}

Extensions can’t add properties.
Nothing is wrong with it.
didSet takes a parameter.
c is not a character.

مرجع: The Swift Programming Language: Language Guide: Extensions: Computed Properties

س 20. didSet and willSet are examples of _?

Property observers
Key properties
All of these answers
newOld value calls

مرجع: The Swift Programming Language: Language Guide: الخصائص

س 21. ما هو الخطأ في هذا الرمز?

self.callback = {
  self.attempts += 1
  self.downloadFailed()
}

Use of self inside the closure causes retain cycle.
You cannot assign a value to a closure in this manner.
You need to define the type of closure explicitly.
There is nothing wrong with this code.

مرجع: The Swift Programming Language: Language Guide: Automatic Reference Counting: Strong Reference Cycles for Closures

Q22. How many values does vals have after this code is executed?

var vals = Set<String> = ["4", "5", "6"]
vals.insert("5")

ثلاثة
أربعة
Eight
This code contains an error.

مرجع: The Swift Programming Language: Language Guide: Collection Types: مجموعات

Q23. How can you avoid a strong reference cycle in a closure?

Use a capture list to set class instances of weak أو unowned.
You can’t, there will always be a danger of strong reference cycles inside a closure.
Initialize the closure as read-only.
Declare the closure variable as lazy.

مرجع: The Swift Programming Language: Language Guide: Automatic Reference Counting

س 24. ما هو الخطأ في هذا الرمز?

if let s = String.init("some string") {
  print(s)
}

هذه String initializer does not return an optional.
String does not have an initializer that can take a String.
= is not a comparison.
Nothing is wrong with this code.

مرجع: The Swift Programming Language: Language Guide: أساسيات: Optionals

Q25. Which code snippet correctly creates a typealias closure?

typealias CustomClosure = () -> ()
typealias CustomClosure { () -> () }
typealias CustomClosure -> () -> ()
typealias CustomClosure -> () {}

مرجع: The Swift Programming Language: Language Reference: Declarations: Type Alias Declaration

س 26. How do you reference class members from within a class?

self
instance
class
this

مرجع: The Swift Programming Language: Language Guide: أساليب: Instance Methods

Q27. All value types in Swift are _ under the hood?

Structs
البرمجة الشيئية PLC
Optionals
Generics

مرجع: The Swift Programming Language: Language Guide: Structures and Classes

س 28. What is the correct way to add a value to this array?

var strings = [1, 2, 3]

All of these answers
strings.append(4)
strings.insert(5, at: 1)
strings += [5]

مرجع: The Swift Programming Language: Language Guide: Collection Types: المصفوفات

س 29. How many times will this loop be executed?

for i in 0...100 {
  print(i)
}

المراجع:

Q30. What can AnyObject represent?

An instance of any class
An instance of function type
All of these answers
An instance of an optional type

مرجع: The Swift Programming Language: Language Guide: Type Casting: Type Casting for Any and AnyObject

س 31. What is the value of t after this code is executed?

let names = ["Larry", "Sven", "Bear"]
let t = names.enumerated().first().offset

This code does not compile. / This code is invalid.
0
1
Larry

المراجع:

Q32. What is the value of test after this code executes?

let vt = (name: "ABC", val: 5)
let test = vt.0

ABC
0
5
name

المراجع:

على ___. What is the base class in this code?

class LSN: MMM {
}

MMM
LSN
There is no base class.
This code is invalid.

مرجع: The Swift Programming Language: Language Guide: ميراث: Subclassing

س 34. What does this code print to the console?

var userLocation: String = "Home" {
  willSet(newValue) {
    print("About to set userLocation to \(newValue)...")
  }

  didSet {
    if userLocation != oldValue {
      print("userLocation updated with new value!")
    } else {
      print("userLocation already set to that value...")
    }
  }
}

userLocation = "Work"

About to set userLocation to Work... userLocation updated with new value!
About to set userLocation to Work... userLocation already set to that value...
About to set userLocation to Home... userLocation updated to new value!
Error

مرجع: The Swift Programming Language: Language Guide: الخصائص: Property Observers

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت. What must a convenience initializer call?

A base class convenience initializer
Either a designated or another convenience initializer
A designated initializer
None of these answers

مرجع: The Swift Programming Language: Language Guide: Initialization: Class Inheritance and Initialization

Q36. Which object allows you access to specify that a block of code runs in a background thread?

DispatchQueue.visible
DispatchQueue.global
errorExample need to be labeled as throws.
DispatchQueue.background

مرجع: Apple Developer: كابل بيانات: Dispatch: DispatchQueue

Q37. What is the inferred type of x?

let x = ["a", "b", "c"]

String[]
Array<String>
Set<String>
Array<Character>

مرجع: The Swift Programming Language: Language Guide: Collection Types: المصفوفات

Q38. What is the value of `oThings` after this code is executed?

let nThings: [Any] = [1, "2", "three"]
let oThings = nThings.reduce("") { "\($0)\($1)" }

11212ثلاثة
115
12ثلاثة
لا شئ, this code is invalid.

مرجع: Apple Developer: كابل بيانات: سريع: مجموعة مصفوفة: reduce(_:_:)

Q39. How would you call a function that throws errors and also returns a value?

!try
try?
try!
?try

مرجع: The Swift Programming Language: Language Guide: Error Handling: Handling Errors

س 40. ما هو الخطأ في هذا الرمز?

protocol TUI {
  func add(x1: Int, x2: Int) -> Int {
    return x1 + x2
  }
}

Protocol functions cannot have return types.
Protocol functions cannot have implementations.
Nothing is wrong with it.
add is a reserved keyword.

مرجع:

س 41. In this code, what are `wheels` و `doors` examples of?

class Car {
  var wheels: Int = 4
  let doors = 4
}

Class members
This code is invalid
Class fields
Class properties

مرجع:

س 42. How do you designated a failable initializer?

You cannot
deinit
init?
init

مرجع:

س 43. What is printed when this code is executed?

let dbl = Double.init("5a")
print(dbl ?? ".asString()")

five
5a
.asString()
5

مرجع:

س 44. In the function below, what are `this` و `toThat` examples of?

func add(this x: Int, toThat y: Int) { }

None of these answers
Local terms
Argument labels
Parameters names

مرجع: The Swift Programming Language: Language Guide: المهام

س 45. ما هو الخطأ في هذا الرمز?

for (key, value) in [1: "one", 2: "two"] {
  print(key, value)
}

The interaction source is invalid
The interaction variable is invalid
There is nothing wrong with this code
The comma in the print is misplaced

مرجع: The Swift Programming Language: Language Guide: تدفق التحكم: For-In Loops

س 46. Which of these choices is associated with unit testing?

XCTest
All of these answers
@testable
XCTAssert

مرجع:

Q47. In the code below, what is width an example of?

class Square {
  var height: Int = 0
  var width: Int {
    return height
  }
}

This code contains error
A closure
A computed property
Lazy loading

مرجع:

س 48. What data type is this an example of?

let vals = ("val", 1)

قاموس
A tuple
An optional
This code contains error

مرجع:

Q49. ما هو الخطأ في هذا الرمز?

var x = 5
x = 10.0

You cannot assign a Double to a variable of type Int
x is undefined
x is a constant
x has no type

مرجع: The Swift Programming Language: Language Guide: أساسيات

س 50. What will this code print to the console?

var items = ["a": 1, "b": 2, "c": "test"] as [String: Any]
items["c"] = nil
print(items["c"] as Any)

أي
اختبار
1,2,3
nil

المراجع:

س 51. ما هو الخطأ في هذا الرمز?

let val = 5.0 + 10

There is nothing wrong with this code
val is a constant and cannot be changed
5.0 و 10 are different types
There is no semicolon

مرجع: The Swift Programming Language: Language Guide: أساسيات: Type Safety and Type Inference

Q52. How many parameters does the initializer for Test have?

struct Test {
  var score: Int
  var date: Date
}

Zero
This code contains an error
اثنين
Structs do not have initializers

مرجع: The Swift Programming Language: Language Guide: Initialization

Q53. What prints to the console when executing this code?

let x = try? String.init("test")
print(x)

nil
لا شئ – this code contains an error
اختياري(“اختبار”)
اختبار

المراجع:

س 54. How can you sort this array?

var vals = [1, 2, 3]

vals.sort { $0 < $1 }
vals.sort { (s1, s2) in s1 < s2 }
vals.sort(by: <)
All of these answers

مرجع: Apple Developer: كابل بيانات: سريع: مجموعة مصفوفة: نوع()

Q55. DispatchQueue.main.async takes a block that will be

Not executed
Executed in the main queue
None of these answers
Executed on the background thread

مرجع: Apple Developer: كابل بيانات: Dispatch: DispatchQueue: async(مجموعة:qos:flags:نفذ - اعدم:)

س 56. When is deinit called?

When a class instance needs memory
All of these answers
When the executable code is finished
When a class instance is being removed from memory

مرجع: The Swift Programming Language: Language Guide: Deinitialization

Q57. How do you declare an optional String?

String?
Optional[String]
[String]?
?String

مرجع: The Swift Programming Language: Language Guide: أساسيات: Optionals

س 58. How many times this code will be executed? / How many times will this loop be performed?

for i in ["0", "1"] {
  print(i)
}

واحد
اثنين
ثلاثة
This code does not compile

مرجع: The Swift Programming Language: Language Guide: تدفق التحكم: For-In Loops

س 59. What does this code print?

let names = ["Bear", "Tony", "Svante"]
print(names[1] + "Bear")

1Bear
BearBear
TonyBear
لا شئ, this code is invalid

المراجع:

س 60. What is true of this code?

let name: String?

name can hold only a string value.
name can hold either a string or nil value.
Optional values cannot be let نظام الري الذكي.
Only non-empty string variables can be stored in name.

مرجع: The Swift Programming Language: Language Guide: أساسيات: Optionals

س 61. What is the value of `val` after this code is executed?

let i = 5
let val = i * 6.0

This code is invalid.
6
30
0

مرجع: The Swift Programming Language: Language Guide: أساسيات: Type Safety and Type Inference

س 62. What does this code print?

enum Positions: Int {
  case first, second, third, other
}

print (Positions.other.rawValue)

3
0
آخر
nil

مرجع: The Swift Programming Language: Language Guide: أساسيات: Raw Values

س 63. What is printed to the console when this code is executed?

"t".forEach { (char) in
  print(char)
}

nil
لا شئ, since the code contains an error
ر
zero

المراجع:

س 64. What prints when this code is executed?

let s1 = ["1", "2", "3"]
  .filter { $0 > "0" }
  .sorted { $0 > $1 }
print(s1)

[]
[“3”, “2”, “1”]
[321]
[“1”, “2”, “3”]

المراجع:

س 65. What enumeration feature allows them to store case-specific data?

Associated values
Integral values
Raw values
Custom values

مرجع: The Swift Programming Language: Language Guide: Enumerations: Associated Values

س 66. In the code below, AOM must be a(ن)?

class AmP: MMM, AOM { }

Class
Protocol
Enumeration
Struct

المراجع:

Q67. What is the value of numbers in the code below?

let numbers = [1, 2, 3, 4, 5, 6].filter { $0 % 2 == 0 }

[1, 3, 5]
[]
[2, 4, 6]
nil

مرجع: Apple Developer: كابل بيانات: سريع: Swift Standard Library: Collections: Sequence and Collection Protocols: تسلسل: منقي()

Q68. What is the type of `vals` in this code?

let vals = ["a", 1, "Hi"]

مجموعة مصفوفة(char)
[أي]
مجموعة مصفوفة
[Generic]

مرجع: The Swift Programming Language: Language Guide: Type Casting

Q69. How can you extract val to `x` in tuple `vt`

let vt = (name: "ABC", val: 5)

let x = vt.1
All of these answers
let x = vt.val
يترك (_, س) = vt

مرجع: The Swift Programming Language: Language Guide: أساسيات: مجموعات

س 70. What is the type of x?

let x = try? String.init(from: decoder)

String
String?
String!
try?

مرجع: The Swift Programming Language: Language Guide: Error Handling: Handling Errors

س 71. How many times is this loop executed?

let loopx = 5
repeat {
  print (loopx)
} while loopx < 6

Six
Zero
Five
Infinite

مرجع: The Swift Programming Language: Language Guide: تدفق التحكم: While Loops

التحكم في مخاطر سلامة العمليات. How many values does vals have after this code is executed?

var vals: Set<String> = ["4", "5", "6"]
vals.insert("5")

This code contains an error.
Eight
ثلاثة
أربعة

مرجع: The Swift Programming Language: Language Guide: Collection Types: مجموعات

Q73. What is the base class in this code ?

class LSN: MMM{ }

MMM
LSN
There is no base class.
This code is invalid.

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LinkedIn skill assessment answers and questions — Swift