Swift学习笔记协议

protocol SomeProtocol {
    var musBeSettable : Int { get set}
    var doesNotNeedToBeSettable: Int { get }
    static func someTypeMethod()
}

protocol AnotherProtocol {
    static var someTypeProperty: Int { get set }
}

protocol FullyNamed {
    var fullName: String { get }
}
struct Person: FullyNamed {
    var fullName: String
}
let john = Person(fullName: "John Appleseed")

class Starship: FullyNamed {
    var prefix: String?
    var name: String
    init(name: String, prefix: String? = nil){
        self.name = name
        self.prefix = prefix
    }
    var fullName: String {
        return (prefix != nil ? prefix! + " " : "") + name
    }
}
var ncc1701 = Starship(name: "Enterprise", prefix: "USS")

protocol RandomNumberGenerator {
    func random() -> Double
}

class LinearCongruentialGenerator: RandomNumberGenerator {
    var lastRandom = 42.0
    let m = 139968.0
    let a = 3877.0
    let c = 29573.0
    func random() -> Double {
        lastRandom = ((lastRandom * a + c) % m)
        return lastRandom / m
    }
}
let generator = LinearCongruentialGenerator()
generator.random()

protocol Togglable {
    mutating func toggle()
}

enum OnOffswitch: Togglable {
    case Off,On
    mutating func toggle() {
        switch self {
        case Off:
            self = On
        case On:
            self = Off
        }
    }
}

var lightSwitch = OnOffswitch.Off
lightSwitch.toggle()

class Dice {
    let sides: Int
    let generator: RandomNumberGenerator
    init(sides: Int, generator: RandomNumberGenerator){
        self.sides = sides
        self.generator = generator
    }
    func roll() ->Int {
        return Int(generator.random() * Double(sides) + 1)
    }
}

var d6 = Dice(sides: 6, generator: LinearCongruentialGenerator())

for _ in 1...5 {
    d6.roll()
}
protocol DiceGame {
    var dice: Dice { get }
    func play()
}
protocol DiceGameDelegate {
    func gameDidStart(game: DiceGame)
    func game(game: DiceGame, didStartNewTurnWithDiceRoll diceRoll: Int)
    func gameDidEnd(game: DiceGame)
}

class SnakesAndLadders: DiceGame {
    let finalSquare = 25
    let dice = Dice(sides: 6, generator: LinearCongruentialGenerator())
    var square = 0
    var board: [Int]
    init() {
        board = [Int](count: finalSquare + 1, repeatedValue: 0)
        board[03] = +08; board[06] = +11; board[09] = +09; board[10] = +02
        board[14] = -10; board[19] = -11; board[22] = -02; board[24] = -08
    }
    var delegate: DiceGameDelegate?
    func play() {
        square = 0
        delegate?.gameDidStart(self)
        gameLoop: while square != finalSquare {
            let diceRoll = dice.roll()
            delegate?.game(self, didStartNewTurnWithDiceRoll: diceRoll)
            switch square + diceRoll {
            case finalSquare:
                break gameLoop
            case let newSquare where newSquare > finalSquare:
                continue gameLoop
            default:
                square += diceRoll
                square += board[square]
            }
        }
        delegate?.gameDidEnd(self)
    }
}
class DiceGameTracker: DiceGameDelegate {
    var numberOfTurns = 0
    func gameDidStart(game: DiceGame) {
        numberOfTurns = 0
        if game is SnakesAndLadders {
            println("Started a new game of Snakes and Ladders")
        }
        println("The game is using a \(game.dice.sides)-sided dice")
    }
    func game(game: DiceGame, didStartNewTurnWithDiceRoll diceRoll: Int) {
        ++numberOfTurns
        println("Rolled a \(diceRoll)")
    }
    func gameDidEnd(game: DiceGame) {
        println("The game lasted for \(numberOfTurns) turns")
    }
}
let tracker = DiceGameTracker()
let game = SnakesAndLadders()
game.delegate = tracker
game.play()


protocol TextRepresentable {
    func asText() -> String
}

extension Dice: TextRepresentable {
    func asText() -> String {
        return "A \(sides)-sided dice"
    }
}

let d12 = Dice(sides: 12,generator: LinearCongruentialGenerator())
d12.asText()

struct Hamster {
    var name: String
    func asText() -> String {
        return "A hamster named \(name)"
    }
}
extension Hamster: TextRepresentable {}
let simonTheHamster = Hamster(name: "Simon")
let somethingTextRepresentable: TextRepresentable = simonTheHamster
println(somethingTextRepresentable.asText())

let things: [TextRepresentable] = [ d12, simonTheHamster]
for thing in things {
    println(thing.asText())
}
protocol Named {
    var name: String { get }
}
protocol Aged {
    var age: Int { get }
}
struct Person12: Named, Aged {
    var name: String
    var age: Int
}

func wishHappyBirthday(celebrator: protocol<Named,Aged>){
    println(celebrator.age)
    println(celebrator.name)
}
let birthdayPerson = Person12(name: "Malcolm", age: 21)
wishHappyBirthday(birthdayPerson)

protocol HasArea {
    var area: Double { get }
}

class Circle: HasArea {
    let pi = 3.1415927
    var radius: Double
    var area: Double { return pi * radius * radius }
    init(radius: Double) { self.radius = radius }
}

class Country: HasArea{
    var area: Double
    init(area: Double) { self.area = area }
}
class Animal {
    var legs: Int
    init(legs: Int) { self.legs = legs }
}

let objects: [AnyObject] = [
    Circle(radius: 2.0),
    Country(area: 243_610),
    Animal(legs: 4)
]

for object in objects {
    if let objectWithArea = object as? HasArea {
        objectWithArea.area
    }
}

swift里的协议与C#中的接口类似