README.md

Operator Questions 1 ~ 6

1) What are the conditional statements available in Swift?

Answer

• if
• if-else
• if-else ladder
• switch

let isAlien: Bool = true

// if
if isAlien {
  print("Alien")
}

// if - else
if isAlien {
  print("Alien")
} else {
  print("Probably Human")
}

// if - else ladder
if isAlien {
  print("Alien")
} else if isAlien != true {
  print("Probably Human")
} else {
  print("What else?")
}

// switch
switch isAlien {
  case true:
    print("Alien")
  case false:
    print("Probably Human")
}

2) What is fast enumeration in Swift?

Answer

• Process of iterating through all elements of a collection in an efficient way. It is faster than general for loop.

let numbers: [Int] = [1, 2, 3, 4, 5, 6, 7, 8, 9]
for number in numbers {
  print(number) //1, 2, 3, 4, 5, 6, 7, 8, 9
}

3) What is the difference between 'while' and 'repeat-while loops' in swift?

Answer

• While is entry control loop whereas do-while is exit control loop
• entry control loop versus exit control loop

// Enter Loop
var i: Int = 0

while i < 5 {
  print(i)
  i += 1
}

// Exit Loop
var j: Int = 0

repeat {
  print(i)
  i += 1
} while i < 5

4) What is switch case and how to declare a swift switch case?

Answer

• Switch is one of the conditional statements. It is an alternate to general if-else ladder statement.

let input: Int = 10

switch input {
  case 0:
    print("Value falls under 0")
  case 1...5:
    print("Value falles between 1 to 5")
  case 6,7,8,9:
    print("Value falls between 6 to 9")
  case 10:
    print("Value is 10")
  default:
    print("Not matched anywhere")
}

Warning

• You don't need to use break but you can use break keyword when you don't want to execute code.

Professional Tips

• Use switch when handling network status code.

5) Is default case necessary in Swift's Switch case?

Answer

• Default case is necessary in switch case, otherwise, you will see Switch must be exhasutive message.

6) What is Fall-through keyword in swift?

Answer

• Fall-through executes the next followed case irrespective of case matching. Place dependent case below the fall-through case

let input: Int = 15

switch input {
case 0:
    print("Value falls under 0")
case 11...15:
    print("Value falls between 11 to 15")
    fallthrough
case 9:
    #warning("This line will be executed when value is 11...15!!!")
    print("Value is 9 and this will be executed when value is between 11...15")
case 10:
    print("Value is 10")
default:
    break
}

Table Of Contents

Section 1, Data Type

Section 2, Operator

Section 3, Conditional Statement

Section 4, Enum

Section 5, functions

Section 6, struct

Section 7, initializers

Section 8, closures

Section 9, OOP

Section 10, static type vs dynamic type

Section 11, optional

Section 12, generic

Section 13, subscript

Section 14, access specifier

Section 15, higher order function

Section 16, delegate

Section 17, extension

Section 18, Memory Management

Section 19, protocols

Section 20, collections

Section 21, KVO and KVC

Section 22, Exception Handling

Section 23, Framework

Section 24, Objective-C