Swift Basic

gistfile1.swift

// Playground - noun: a place where people can play

import UIKit

// constant and variable

//let langName: String = "Swift"
//var version: Double = 1.0
//let introduced: Int = 2014
//let isAwesome: Boolean = true

let langName = "Swift"
var version = 1.0
let introduced = 2014
let isAwesome = true

// unicode names
// String

let someString = "I appear to be a string"

// string is character
for char in "mouse" {
    println(char)
}

// complex strings
let complex1 = 3, complex2 = 4
let complexResult = "\(complex1) times \(complex2) is \(complex1 * complex2)"
println(complexResult)

//array and dictionary
var names = ["Anna", "Alex", "Brain", "Jack", 4]
var numOfLegs = ["ant":6, "snake":0, "cheetah":4]

for (anName, legCount) in numOfLegs {
    println("\(anName) have \(legCount) legs")
}

// optionals 
//ex: int or nothing
let possilbeLegcount: Int? = numOfLegs["aardvark"]

// condition - if else
if possilbeLegcount == nil {
    println("aardvark wasn't found")
} else {
    let legCount: Int? = possilbeLegcount
    println("aardvark has \(legCount) legs")
}


// typed collections
var names1: [String] = ["Ann", "Alex"]

// range
for num in 1...5 {
    println("\(num) times 4 is \(num * 4)")
}

// function
func buildGreeting(name: String = "World") -> String {
    return "Hello " + name
}
println(buildGreeting())

func refreshWebPage() -> (Int, String) {
    return (200, "Success")
}
let (statusCode, statusmessage) = refreshWebPage()
println("Received \(statusCode): \(statusmessage)")

// Closures
let greetingPrinter: () -> () = {
    println("Hello world!")
}
println(greetingPrinter())

// Class
class Vehicle {
    var numberOfWheels = 0
    var description: String {
    get {
        return "\(numberOfWheels) wheels"
    }
    }
}

var test = Vehicle()
println(test.description)

// subclass
class Bicycle: Vehicle {
    init() {
        super.init()
        numberOfWheels = 2
    }
}
let myBike = Bicycle()
println(myBike.description)

class Car: Vehicle {
    var speed = 0.0
    init()  {
        super.init()
        numberOfWheels = 4
    }
    override var description: String {
        return super.description + ", \(speed) mph"
    }
}
let myCar = Car()

// willSet, didSet
class ParentCar: Car {
    init() {
        super.init()
    }
    override var speed: Double {
    willSet {
        if newValue > 65.0 {
            println("Careful!!")
        }
    }
    }
}

//method
class Counter {
    var count = 0
    func incrementBy(amount: Int) {
        count += amount
    }
    func resetToCount(count: Int) {
        self.count = count
    }
}

// struct
// use struct or class?
// struct - pass by value
// class - pass by reference

struct Point {
    var x, y: Double
    
}

// enum
enum CompassPoint {
    case North, South, East, West
}

var directionToHead = CompassPoint.West
directionToHead = .East

// enum: associated values & properties
enum TrainStatus {
    case OnTime
    case Delayed(Int)
    init() {
        self = OnTime
    }
    var description: String {
        switch self {
        case OnTime:
            return "on time"
        case Delayed(let minutes):
            return "delayed by \(minutes) minute(s)"
        }
    }
}
var status = TrainStatus.OnTime
status = .Delayed(42)
println(status.description)

// extensions
extension Int {
    func repetitions(task: () -> ()) {
        for i in 0..<self {
            task()
        }
    }
}

5.repetitions({
    println("Hello!")
})

// generic
struct Stack<T> {
    var elements = [T]()
    
    mutating func push(element: T) {
        elements.append(element)
    }
    
    mutating func pop() -> T {
        return elements.removeLast()
    }
}

var intStack = Stack<Int>()
intStack.push(50)
let lastIn = intStack.pop()

var stringStack = Stack<String>()
stringStack.push("hello")
stringStack.push("world!")
let lastStr = stringStack.pop()