iOS8 Swift Cheat Sheet

iOS8 Swift Cheat Sheet and Quick Reference Guide for iPhone Developers. Swift is the new programming language used in developing applications for Mac OS and iOS,

Arrays

var colors = ["red", "blue"]
var moreColors: String[] = ["orange", "purple"] // explicit type
colors.append("green") // [red, blue, green]
colors += "yellow" // [red, blue, green, yellow]
colors += moreColors // [red, blue, green, yellow, orange, purple]

var days = ["mon", "thu"]
var firstDay = days[0] // mon
days.insert("tue", atIndex: 1) // [mon, tue, thu]
days[2] = "wed" // [mon, tue, wed]
days.removeAtIndex(0) // [tue, wed]

Classes

class Counter {
  var count: Int = 0 
  func inc() { 
    count++
  }
  func add(n: Int) {
    count += n
  }
  func printCount() {
    println("Count: \(count)")
  }
}

var myCount = Counter()
myCount.inc()
myCount.add(2)
myCount.printCount() // Count: 3    
   

Conditionals

//IF STATEMENT
let happy = true
if happy {
 println("We're Happy!")
} else {
 println("We're Sad :('")
}
// We're Happy!

let speed = 28
if speed <= 0 {
 println("Stationary")
} else if speed <= 30 {
 println("Safe speed")
} else {
 println("Too fast!")
}
// Safe speed


//SWITCH STATEMENT
let n = 2
switch n {
 case 1:
  println("It's 1!")
 case 2...4:
   println("It's between 2 and 4!")
 case 5, 6:
  println("It's 5 or 6")
 default:
  println("Its another number!")
}
// It's between 2 and 4!

Constants

let myInt = 1
myInt = 2 // compile-time error!

Dictionaries

var days = ["mon": "monday", "tue": "tuseday"] 
days["tue"] = "tuesday" // change the value for key "tue"
days["wed"] = "wednesday" // add a new key/value pair

var moreDays: Dictionary = ["thu": "thursday", "fri": "friday"]
moreDays["thu"] = nil // remove thu from the dictionary
moreDays.removeValueForKey("fri") // remove fri from the dictionary

Enums

enum CollisionType: Int { 
 case Player = 1 
 case Enemy = 2 
} 
var type = CollisionType.Player

For Loops

for var index = 1; index < 3; ++index {
 // loops with index taking values 1,2 
}
for index in 1..3 {
 // loops with index taking values 1,2
}
for index in 1...3 { 
 // loops with index taking values 1,2,3
}

let colors = ["red", "blue", "yellow"]
for color in colors {
    println("Color: \(color)")
}
// Color: red
// Color: blue
// Color: yellow 

let days = ["mon": "monday", "tue": "tuesday"]
for (shortDay, longDay) in days {
    println("\(shortDay) is short for \(longDay)")
}
// mon is short for monday
// tue is short for tuesday

Functions

func iAdd(a: Int, b: Int) -> Int {
  return a + b
}
iAdd(2, 3) // returns 5

func eitherSide(n: Int) -> (nMinusOne: Int, nPlusOne: Int) {
  return (n-1, n+1)
}
eitherSide(5) // returns the tuple (4,6)    

Logical Operators

var happy = true
var sad = !happy // logical NOT, sad = false
var everyoneHappy = happy && sad // logical AND, everyoneHappy = false
var someoneHappy = happy || sad // logical OR, someoneHappy = true

Printing

let name = "swift"
println("Hello")
println("My name is \(name)")
print("See you ")
print("later")
/*  
 Hello
 My name is swift
 See you later 
*/

Strings

var myString = "a"
let myImmutableString = "c"
myString += "b" // ab
myString = myString + myImmutableString // abc
myImmutableString += "d" // compile-time error!

let count = 7
let message = "There are \(count) days in a week"

Variables

var myInt = 1 
var myExplicitInt: Int = 1 // explicit type
var x = 1, y = 2, z = 3 // declare multiple integers
myExplicitInt = 2 // set to another integer value