LinkedIn Swift Assessment Quiz Answers

 

LinkedIn Swift Assessment Answers 

LinkedIn Swift Assessment Answers: To find the Skill Assessments, go to your profile and scroll to the Skill section. Select one of the available Skill Assessments you'd like to take. Any results are kept private to you, and if you pass (in the 70th percentile or above), you will have the option to add a “verified skill” badge to your profile.

The LinkedIn Skill Assessments feature allows you to demonstrate your knowledge of the skills you’ve added to your profile. Job posters on LinkedIn can also add Skill Assessments as part of the job application process. This allows job posters to more efficiently and accurately verify the crucial skills a candidate should have for a role.

The topics in the Swift assessment include:

• Types
• Classes and Structs
• General
• Closures and Functions
• Control Flow
• Options
• Threading
• Protocols
• Extensions
• Unit Testing

Question Format

Multiple Choice

Language

English

LinkedIn Swift Assessment Questions and Answers

Q1. What is this code an example of?

let val = (Double)6

•  an error
•  typecasting
•  assignment
•  initialization

Q2. What is the error in this code?

let x = 5

guard x == 5 { return }

•  The guard is missing the else.
•  Nothing is wrong.
•  The guard is missing a then.
•  The comparison is wrong.

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

enum Direction {

  case north, south, east, west

}

•  There is none.
•  String
•  Any
•  Int

Q4. Why is dispatch group 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.

Q5. What is this code an example of?  

let val = 5

print("value is: \(val)")

•  string interpolation
•  string compilation
•  method chaining
•  string concatenation

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

Q7. What does this code print?

typealias Thing = [String, Any]

var stuff: Thing

print(type(of: stuff))

•  Dictionary<String, Any> (To print this then code in question has to be type alias Thing = [String: Any])
•  Dictionary
•  ERROR (If the code in question is really like that.)
•  Thing

Q8. What is the value of y?

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

let y = x[0]

•  This code contains an error
•  1
•  2
•  nil

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

var test = 1 == 1

•  TRUE
•  YES
•  1
•  This code contains an error

Q10. What is the value of y?

var x: Int?

let y = x ?? 5

•  5
•  0
•  nil
•  This code contains an error

Q11. What is the type of this function?

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

•  Int
•  (Int, Int) -> Int
•  Int
•  Functions don't have types.

Q12. 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)

Q13. The Codable protocol is **_**?

•  a combination of Encodable and Decodable
•  not a true protocol <<<<---Possibly correct as it's a type alias of Encodable and Decodable
•  required of all classes
•  automatically included in all classes

Q14. What is the type of value1 in this code?

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

•  String
•  Int
•  null
•  test.count

Q15. When a function takes a closure as a parameter, when do you want to mark it as escaping?

•  when it's executed after the function returns
•  when its scope is undefined
•  when is lazy-loaded
•  all of these answers

Q16. What's wrong with this code?

class Person {

  var name: String

  var address: String

}

•  A person has no initializers.
•  A person has no base class.
•  var name is not formatted correctly.
•  the address is a keyword.

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.

Q18. What describes this line of code?

let val = 5

•  a constant named value of type Int
•  a variable named value of type item
•  a constant named value of type Number
•  a variable named value of type Int

Q19. What is the error in this code?

extension String {

  var firstLetter: Character = "c" {

    didSet {

      print("new value")

    }

  }

}

•  Extensions can't add properties. // although extensions technically can't contain stored properties
•  Nothing is wrong with it.
•  didSet takes a parameter.
•  c is not a character.

Q20. didSet and willSet are examples of \***\*\_\*\***?

•  property observers
•  key properties
•  all of these answers
•  newOld value calls

Q21. What is wrong with this code?

self.callback = {

  self.attempts += 1

  self.downloadFailed()

}

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

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

var vals = Set<String> = ["4", "5", "6"]

vals.insert("5")

•  three
•  four
•  eight
•  This code contains an error.

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

•  Use a capture list to set class instances of weak or 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.

Q24. What is wrong with this code?

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

  print(s)

}

•  This 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.

Q25. Which code snippet correctly creates a type alias closure?

•  typealias CustomClosure: () -> ()
•  typealias CustomClosure { () -> () }
•  typealias CustomClosure -> () -> ()
•  typealias CustomClosure -> () {}

Q26. How do you reference class members from within a class?

•  self
•  instance
•  class
•  this

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

•  structs
•  classes
•  optionals
•  generics

Q28. What is the correct way to ass a value to this array?

var strings = [1, 2, 3]

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

Q29. How many times will this loop be executed?

for i in 0...100 {

  print(i)

}

•  0
•  101
•  99
•  100

Q30. What can AnyObject represent?

•  an instance of any class
•  an instance of an optional type
•  an instance of a function type
•  all of these answers

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

Q31. What does this code print?

typealias Thing = [String:Any]

var stuff : Thing

print(type(of:stuff))

•  Dictionary
•  ERROR
•  Thing
•  Dictionary<String, Any>

Q32. What is the value of the test in this code?

var test = 1 == 1

•  TRUE
•  1
•  This code contains an error.
•  YES

Q33. What is the value of y?

var x : Int?

let y = x ?? 5

•  0
•  nil
•  This code contains an error.
•  5

Q34. What is the value of y?

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

let y = x[0]

•  1
•  nil
•  This code contains an error.
•  2

Q35. What is the value of t after this code is executed?

let names = ["Larry", "Sven", "Bear"]

let t = names.enumerated().first().offset

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

Q36. What is the value of the test after this code executes?

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

let test = vt.0

•  ABC
•  0
•  5
•  name

Q37. What is the base class in this code?

class LSN: MMM {

}

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

Q38. 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 user location to Work… user location updated with new value!
•  About to set user location to Work… user location already set to that value…
•  About to set user location to Home… user location updated to new value!
•  ERROR

Q39. 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

Q40. 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

Q41. What is the inferred type of x?

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

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

Q42. What is the value of things after this code is executed?

let nThings: [Any] = [1, "2", "three"]

let oThings = nThings.reduce("") { "\($0)\($1)" }

•  11212three
•  115
•  12three
•  Nothing, this code is invalid.

Q43. How would you call a function that throws errors and also returns a value?

•  !try
•  try?
•  try!
•  ?try

Q44. What is wrong with this code?

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.

Q45. In this code, what are wheels and doors examples of?

class Car {

  var wheels: Int = 4

  let doors = 4

}

•  class members
•  This code is invalid.
•  class fields
•  class properties

Q46. How do you designate a failable initializer?

•  init?
•  deinit
•  init
•  You can't.

Q46. How do you designate a failable initializer?

•  You cannot deinit
•  init?
•  init

Q47. What is printed when this code is executed?

let dbl = Double.init("5a")

print(dbl ?? ".asString()")

•  five
•  5a
•  .asString()
•  5

Q48. In the function below, what are these and what are examples of?

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

•  none of these answers
•  local terms
•  argument labels
•  parameters names

Q49. What is wrong with this code?

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

  print (s)

}

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

Q50. What is wrong with this code?

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

Q51. Which of these choices is associated with unit testing?

•  XCTest
•  all of these answers
•  @testable
•  XCAssert

Q52. In the code below, what is width an example of?

class Square{

  var height: Int = 0

  var width : Int {

    return height

  }

}

•  This code contains an error
•  a closure
•  a computed property
•  lazy loading

Q53. What data type is this an example of?

let vals = ("val", 1)

•  a dictionary
•  a tuple
•  an optional
•  This code contains an error

Q54. What is wrong with this code?

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

Q55. What is the type of x: let x = try?

String.init(from: decoder)

•  String
•  String?
•  String!
•  try?

Q56. 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)

•  Any
•  test
•  1,2,3
•  nil

Q57. What is wrong with this code?

let val = 5.0 + 10

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

Q58. How many parameters does the initializer for the Test have?

struct Test{

  var score: Int

  var date: Date

}

•  zero
•  This code contains an error
•  two
•  Structs do not have initializers

Q59. What prints to the console when executing this code?

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

print(x)

•  nil
•  Nothing - this code contains an error
•  Optional("test")
•  test

Q60. 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

Q61. What is printed when this code is executed?

let dbl = Double.init("5a")

print(dbl ?? ".asString()")

•  5a
•  5
•  five
•  asString()

Q62. 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

Q63. What is the value of the test after this code executes?

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

let test = vt.0

•  ABC
•  name
•  5
•  0

Q64. 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

Q65. How do you declare an optional String?

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

Q66. Why is a dispatch group used in a certain situation?

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

Q67. How many times this code will be executed? —OR— How many times will this loop be performed?

for i in ["0", "1"]{

  print(i)

}

•  one
•  two
•  three
•  This code does not compile

Q68. What does this code print?

let names = ["Bear", "Tony", "Svante"]

print(names[1]+"Bear")

•  1Bear
•  BearBear
•  TonyBear
•  Nothing, this code is invalid

Q69. 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 constants.
•  Only non-empty string variables can be stored in the name.

Q70. What is the value of Val after this code is executed?

let i = 5

let val = i * 6.0

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