Control Flow


  • conditional
  • if statement
  • If-else statement
  • interval matching
  • logical operators
  • switch
  • ternary operator

Excerpt From: Apple Education. “App Development with Swift.” Apple Inc. - Education, 2017. iBooks. https://itunes.apple.com/WebObjects/MZStore.woa/wa/viewBook?id=1219117996

Logical Operators

Boolean Values

You can assign the results of a logical operator to a Bool constant or variable in order to check or access the value later. Bool values can only be true or false. In the following code, the Bool statement determines that number doesn't qualify as isSmallNumber:

let number = 1000
let isSmallNumber = number < 10 
// number is not less than 10, so isSmallNumber is assigned 
a `false` value 

Logical not is !

if and if-else

let temperature = 100
if temperature >= 100 {
  print("The water is boiling.")
let temperature = 100
if temperature >= 100 {
  print("The water is boiling.")
} else {
  print("The water is not boiling.")


let numberOfWheels = 2
switch numberOfWheels {
case 1:
case 2:
case 3:
case 4:
    print("That's a lot of wheels!")

Better switch statements.

let character = "z"
switch character {
case "a", "e", "i", "o", "u" :
    print("This character is a vowel.")
    print("This character is a consonant.")

Interval matching.

switch distance {
case 0...9:
    print("Your destination is close.")
case 10...99:
    print("Your destination is a medium distance from here.")
case 100...999:
    print("Your destination is far from here.")
    print("Are you sure you want to travel this far?")

Ternary Operator

Just like Jaascript

largest = a > b ? a : b