iOS Interview Questions 2020 - Part 1

Questions, Tips and Tricks to clear iOS Interview Questions

Photo from Unsplash

I hope the interview series I published before helped you a lot to understand the iOS developer interview process and brush up with a few interesting topics. Now for a change lets try to test our skills with the below Questions:

Q1. What output will be produced by the code below?

var crew = ["Captain": "Malcolm", "Doctor": "Simon"]  
crew = [:]  
print(crew.count)

Q2. What output will be produced by the code below?

let number = 5  
  
switch number {  
case 0..<5:  
    print("First group")  
case 5...10:  
    print("Second group")  
case 0...5:  
    print("Third group")  
default:  
    print("Fourth group")  
}

Q3. When this code is executed, what will the numbers constant contain?

let numbers = [1, 2, 3].map { [$0, $0] }

Q4. What output will be produced by the code below?

var spaceships = Set<String>()  
spaceships.insert("Serenity")  
spaceships.insert("Enterprise")  
spaceships.insert("TARDIS")  
spaceships.insert("Serenity")  

print(spaceships.count)

Q5. What output will be produced by the code below?

let rounded: Int = round(10.5)  
print("Rounding 10.5 makes \(rounded)")

Q6. What output will be produced by the code below?

func greet(_ name: inout String) {  
    name = name.uppercased()  
    print("Greetings, \(name)!")  
}

var name = "Mal"  
greet(name)  
print("Goodbye, \(name)!")

Q7. What output will be produced by the code below?

let point = (556, 0)

switch point {  
case (let x, 0):  
 print("X was \(x)")  
case (0, let y):  
 print("Y was \(y)")  
case let (x, y):  
 print("X was \(x) and Y was \(y)")  
}

Q8. Read the code below:

var foo: Float = 32  
var bar: Double = 32

Assuming no typecasting, which of the following statements is true?

Q9. What output will be produced by the code below?

let people = [String](repeating: "Malkovitch", count: 2)  
print(people)

Q10. When this code is executed, what value does the result contain?

func sum(numbers: Int...) -> Int {  
    var result = 0  
  
    for number in numbers {  
        result += number  
    }  
  
    return result  
}  

let result = sum(numbers: [1, 2, 3, 4, 5])

Q11. What output will be produced by the code below?

let crew = NSMutableDictionary()  
crew.setValue("Kryten", forKey: "Mechanoid")  
print(crew.count)

Q12. What output will be produced by the code below?

enum MyError: Error {  
    case broken  
    case busted  
    case badgered  
}  
  
func willThrowAnError() {  
    throw MyError.busted  
}  
  
do {  
    try willThrowAnError()  
} catch MyError.busted {  
    print("Code was busted!")  
} catch {  
    print("Code just didn't work")  
}

Q13. When this code is executed, what will the numbers constant contain?

let numbers = [1, 2, 3].flatMap { [$0, $0] }

Q14. When this code is executed, what data type does converted number have?

let possibleNumber = "1701"  
let convertedNumber = Int(possibleNumber)

Q15. What output will be produced by the code below?

let names = ["Pilot": "Wash", "Doctor": "Simon"]  
let doctor = names["doctor"] ?? "Bones"  
print(doctor)

Answers:

1. (1) 0
2. (2) Second group
3. (5) [[1, 1], [2, 2], [3, 3]]
4. (3) 3
5. (6) This code will not compile
6. (6) This code will not compile
7. (1) X was 556
8. (2) Neither variable can be assigned to the other
9. (3) ["Malkovitch", "Malkovitch"] (an array)
10. (7) This code will not compile
11. (2) 1
12. (5) This code will not compile
13. (1) [1, 1, 2, 2, 3, 3]
14. (2) Int?
15. (2) "Bones"

Thank you! will meet you in part 2 with a different set of questions 🚀

References:

Swift By Sundell
Hacking With Swift
Raywenderlich
Swift Documentation by Apple