[swift] code log, day 4

iBooks 의 SWIFT 4 를 통해 언어 공부 중입니다. 이때 사용된 책 속의 코드 및 연습문제 등의 코드 로그입니다.

아래 코드들은 Github 에서도 다운받을 수 있습니다.

SWIFT_Playground_Excersice: https://github.com/youp-han/SWIFT_Playground_Excersice

//------------------------------------------------------------

// 코드 로그 입니다.

// Day 4

// Enumerationas and Structures

// Default 로 raw value 는 0 에서 시작하지만, 다음의 경우

// case ace = 1에서 시작함.

enum Rank: Int{

    case ace = 1

    case two, three, four, five, six, seven, eight, nine, ten

    case jack, queen, king

    func simpleDescription() -> String{

        switch self{

        case .ace:

            return "ace"

        case .jack:

            return "jack"

        case .queen:

            return "queen"

        case .king:

            return "king"

        default:

            return String(self.rawValue)

        }

    }

}

let ace = Rank.ace

let aceRawValue = ace.rawValue

let two = Rank.two

let twoRawValue = two.rawValue

if let convertedRank = Rank(rawValue:3) {

    let threeDescription = convertedRank.simpleDescription()

print(threeDescription)

}

//enum 2

enum Suit{

    case spades, hearts, diamonds, clubs

    func simpleDescription()->String{

        switch self{

        case .spades:

            return "spades"

        case .hearts:

            return "hearts"

        case .diamonds:

            return "diamonds"

        case .clubs:

            return "clubs"

        }

    }

    

    //experiment

    func color()->String{

        switch self{

        case .spades:

            return "black"

        case .clubs:

            return "black"

        default:

            return "red"

        }

    }

}

let hearts = Suit.hearts

let heartsDescription = hearts.simpleDescription()

let heartsColor = hearts.color()

// enum 3

enum ServerResponse {

    case result (String, String)

    case failure (String)

}

let success = ServerResponse.result("6:00 am", "8:09 pm")

let failure = ServerResponse.failure("Out of cheese")

switch success {

case let .result(sunrise, sunset):

    print("Sunrise is at\(sunrise) and sunset is at \(sunset).")

case let .failure(message):

    print("Failure... \(message)")

}

//struct

// struct vs class

// struct gets copied where classes are passed by reference

struct Card {

    var rank: Rank

    var suit: Suit

    func simpleDescription() -> String {

        return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"

    }

}

let threeOfSpades = Card(rank: .three, suit: .spades)

let threeOfSpedesDescription = threeOfSpades.simpleDescription()

//Protocals and Estensions

//Classes, enum and Structs can adopt protocols

protocol ExampleProtocol {

    var simpleDescription : String { get }

    mutating func adjust()

}

class SimpleClass: ExampleProtocol{

    var simpleDescription: String = "A very simple class"

    var anotherProperty: Int = 52342

    func adjust(){

        simpleDescription += " Now 100% adjusted"

    }

}

var a = SimpleClass()

a.adjust()

let aDescription = a.simpleDescription

struct SimpleStruture: ExampleProtocol {

    var simpleDescription: String = "A simple structure"

    mutating func adjust(){

        simpleDescription += " (adjusted)"

    }

}

var b = SimpleStruture()

b.adjust()

let bDescription = b.simpleDescription

// why mutating func in Structure?

// because, the structure is a value type where class is a reference type

// and to make changes in a function of the structure,

// the function should be mutable

// example

struct Rectangle {

    var height = 1

    var width = 1

    func area() -> Int{

        return height * width

    }

    

    mutating func scaleBy(value: Int) {

        width*=value

        height*=value

    }

}

var rect = Rectangle()

// let rect = Rectangle() will give errors for its a value type (immutable)

rect.area()

rect.scaleBy(value: 3)

rect.area()

// extension of protocol

extension Int: ExampleProtocol {

    var simpleDescription: String {

        return "the number \(self)"

    }

    

    mutating func adjust(){

        self += 42

    }

}

print (7.simpleDescription)

let protocolValue: ExampleProtocol = a

print(protocolValue.simpleDescription)

//print(protocolValue.anotherProperty)

//Error Handling

enum PrinterError: Error{

    case outOfPaper

    case noToner

    case onFire

}

func send(job: Int, toPrinter printerName: String) throws -> String{

    if printerName == "Never Has Toner" {

        throw PrinterError.noToner

    }

    return "Job Sent"

}

do{

    // the following statement throws no error

    // let printerResponse = try send(job: 1040, toPrinter: "Bi Sheng")

     let printerResponse = try send(job: 1040, toPrinter: "Never Has Toner")

    print(printerResponse)

}catch{

    print(error)

}