ソフトウェアエンジニアの技術ブログ：Software engineer tech blog

generic

// Generics

func getThree<T>(x: T){
    print(x)
    print(x)
    print(x)
}

getThree(x: 5)
getThree(x: "Hello")
getThree(x: 2.3)

guard

// func sayHi(_ msg: String?){
//     if let s = msg{
//         print(s)
//     } else {
//         print("value is not set!")
//     }
// }
// sayHi(nil)
// sayHi("hello")

func sayHi(_ msg: String?){
    guard let s = msg else{
        print("value not set!")
        return
    } 
    print(s)
}

sayHi(nil)
sayHi("hello")

例外処理

// 例外処理

enum LoginError: Error{
    case emptyName
    case shortName
}

class User {
    let name: String
    init(_ name: String){
        self.name = name
    }
    func login() throws{
        guard name != "" else {
            throw LoginError.emptyName
        }
        guard name.characters.count > 5 else {
            throw LoginError.shortName
        }
        print("login success")
    }
}
let tom = User("tom")

do {
    try tom.login()
} catch LoginError.emptyName {
    print("please enter your name")
} catch LoginError.shortName{
    print("too short")
}

optional

// class User {
//     var name: String = ""
// }

// let user: User
// user = User()
// user.name = "him"
// let s = user.name.uppercased()
// print(s)

class User {
    var name: String = ""
}

let user: User?
user = User()
user?.name = "him"
if let s = user?.name?.uppercased(){
    print(s)
}

// Implicity Unwrapped Optional

// var msg: String?
var msg: String!
msg = "hello"

// if msg != nil {
//     print(msg!)
// }

print(msg)

protocol

// protocol

protocol Printable {
    var type: String { get }
    var count : Int { get set}
    func printout()
}

class User : Printable{
    let name: String // property
    let type = "Laser"
    var count = 0
    init(_ name: String){
        self.name = name
    }
    func printout(){
        count += 1
        print("\(type): \(count)")
    }
}

let tom = User("tom")
tom.printout()
tom.printout()
tom.printout()

extension

// extension

extension String {
    var length: Int {
        return self.characters.count
    }
}

let msg = "hello"
print(msg.characters.count)
print(msg.length)

protocol Printable {
    func printout()
}

class User{
    let name: String // property
    init(_ name: String){
        self.name = name
    }
}

// extension

extension String {
    var length: Int {
        return self.characters.count
    }
}

let msg = "hello"
print(msg.characters.count)
print(msg.length)

protocol Printable {
    func printout()
}

extension Printable {
    func printout(){
        print("now printing...")
    }
}

class User: Printable{
    let name: String // property
    init(_ name: String){
        self.name = name
    }
}
let tom = User("tom")
tom.printout

値の参照

// Int, Double, Array .. ->値型
// Class -> 参照型

// var original = 10
// var copy = original // original

// original = 20
// print(original)
// print(copy)

class User{
    var name: String // property
    init(_ name: String){
        self.name = name
    }
}

var original = User("tom")
var copy = original // originalのデータが格納されている場所
original.name = "bob"
print(original.name)
print(copy.name)

構造体

// 構造体
// クラスと同機能

struct User{
    var name: String // property
    init(_ name: String){
        self.name = name
    }
    mutating func changeName(){
        self.name = name.Uppercased()
    }
}

var original = User("tom")
var copy = original // originalの値
original.name = "bob"
print(original.name)
print(copy.name)

// 列挙型

enum Direction {
    case right
    case left
}

// var dir: Direction
// // dir = Direction.right
// dir = .right

// switch(dir){
//     case .right:
//         print("right")
//     case .left:
//         print("left")
// }
enum Direction: Int {
    case right = 1
    case left = -1
}
print(Direction.right.rawValue)

class User {
    let name: String // property
    var score: Int
    // init(name: String, score: Int){
    init(_ name: String,_ score: Int){
        self.name = name
        self.score = score
    }
    init(){
        self.name = "bob"
        self.score = 30
    }
}
// let tom = User(name: "tom", score: 23)
let tom = User("tom", 23)
print(tom.name)
print(tom.score)

let bob = User()
print(bob.name)
print(bob.score)

計算プロパティ

class User {
    let name: String // property
    var score: Int
    var level: Int{
        get {
            return Int(score / 10)
        }
        set {
            if newValue >= 0 {
                score = newValue * 10
            }
        }
    }
    init(_ name: String,_ score: Int){
        self.name = name
        self.score = score
    }
    init(){
        self.name = "bob"
        self.score = 30
    }
}

let tom = User("tom", 23)
print(tom.level)
tom.level = 5
print(tom.score)

willSetとdidSet

    let name: String // property
    var score: Int {
        willSet {
            // before change
            print("\(score) -> \(newValue)")
        }
        didSet {
            // after change
            print("Changed: \(score - oldValue)")
            
        }
    }
    init(_ name: String,_ score: Int){
        self.name = name
        self.score = score
    }
}

let tom = User("tom", 23)
tom.score = 53
tom.score = 40

method

class User {
    let name: String // property
    var score: Int
    init(_ name: String,_ score: Int){
        self.name = name
        self.score = score
    }
    // クラスに紐付いた関数はメソッド
    func sayHi(msg: String){
        print("\(msg) \(name)")
    }
}
let tom = User("tom", 23)
// tom.sayHi()
tom.sayHi(msg: "hola")

classの継承

class User {
    let name: String // property
    var score: Int
    init(_ name: String,_ score: Int){
        self.name = name
        self.score = score
    }
    func sayHi(){
        print("hi \(name)")
    }
}

class AdminUser: User {
    func sayHello(){
        print("hello \(name)")
    }
    override func sayHi(){
        print("[admin] hi \(name)")
    }
}
let tom = User("tom", 23)
let bob = AdminUser("bob", 33)
print(bob.name)
print(bob.score)
bob.sayHi()
bob.sayHello()

class User {
    let name: String // property
    var score: Int
    static var count = 0
    init(_ name: String,_ score: Int){
        self.name = name
        self.score = score
        User.count += 1
    }
    func sayHi(){
        print("hi \(name)")
    }
    static func getInfo(){
        print("\(count) instances")
    }
}

User.getInfo()
let tom = User("tom", 23)
User.getInfo()

型キャスト

// asを使った変換　-> 型キャスト
class User {
    let name: String // property
    init(_ name: String){
        self.name = name
    }
}
class AdminUser: User {}

let tom = User("tom")
let bob = AdminUser("bob")

let users: [User] = [tom, bob]

for user in users {
    // if let u = user as? AdminUser{
    //     print(u.name)
    // }
    if user is AdminUser {
        user as! AdminUser
        print(u.name)
    }
}

// var winners: Set<Int> = [3, 5, 8, 8]
var winners: Set = [3, 5, 8, 8]
print(winners)

// var winners: Set<Int> = [3, 5, 8, 8]
var winners: Set = [3, 5, 8, 8]

print(winners.contains(3))
winners.insert(10)
winners.remove(5)
print(winners)
print(winners.count)

let a: Set = [1, 3, 5, 8]
let b: Set = [3, 5, 8, 9]

print(a.union(b))
print(a.intersection(b))
print(a.union(b))
print(a.subtracting(b))

辞書

// var sales: Dictionary<String, Int> = ["kobayashi":200, "kudo":300]
// var sales = ["kobayashi": 200, "kudo": 300]
// sales["kudo"] =  500
// print(sales["kobayashi"] ?? "n.a.")
// sales["yushima"] = 400
// print(sales.count)

// for(key, value) in sales {
//     print("\(key): \(value)")
// }

let d = [String: Int]()
print(d.isEmpty)
[/code

関数

// func sayHi(){
//     print("hi")
// }
// sayHi()

func sayHi()-> String{
    return "hi"
}

print(sayHi())

// func sayHi(){
//     print("hi")
// }
// sayHi()

// func sayHi(name: String){
//     print("hi \(name)")
// }

// sayHi(name: "tom")


// func sayHi(from name: String){
//     print("hi \(name)")
// }

// sayHi(from: "tom")

// func sayHi(_ name: String){
//     print("hi \(name)")
// }

// sayHi("tom")

func sayHi(_ name: String = "tom"){
    print("hi \(name)")
}

sayHi()

func add10(x: inout Int){
    x = x + 10
    print(x)
}

var i = 10
add10(x: &i)

class

class User {
    let name: String // property
    var score: Int
    init(){
        self.name = "me!"
        self.score = 23
    }
    
}

// let uer: User = User()
let user = User()
print(user.name)
print(user.score)
user.score = 26
print(user.score)

var n = 0

while n < 3{
    print(n)
    n += 1
}
&#91;/code&#93;

repeat while
&#91;code&#93;
var n = 0

repeat {
    print(n)
    n += 1
} while n < 3
&#91;/code&#93;

for
&#91;code&#93;
for i in 0...5 {
    print(i)
}
&#91;/code&#93;

for break
&#91;code&#93;
for i in 0...5 {
    if i == 3 {
        break
        continue
    }
    print(i)
}
&#91;/code&#93;

optional
&#91;code&#93;
// let s: Optional<String> = nil
let s: String? = nil

// if s != nil{
//     print(s!)
// }

// optional binding
if let value = s {
    print(value)
}

配列

//var scores:[Int] = [50, 40, 30]

// var scores = [50, 30]

// print(scores[1])

// print(scores.count)
// print(scores.isEmpty)

var names = [String]()
names.append("John")
names.append("adam")
names += ["yokoi"]

for name in names {
    print(name)
}

タプル

// var items = ("apple", 5)
// print(items.0)
// items.1 = 8
// print(items)

// let(product, amount) = items
// print(product)
// print(amount)

// let (product, _) = items
// print(product)

var items = (product: "apple", amount: 5)
print(items.product)

let i: Int = 10
let d = 53.8 // doubleになる

let s = "string"
let flag = true // bool true/false

var x = "five"
x = String(5)
print(x)

バックスラッシュはoption + ¥

// 数値
// + - * / %
// print(10 / 3)
// print(10.0 / 3)

var y = 10
y *= 10

print("hello" + " world!")
print("y is \(y - 5)")

&& || !

let score = 82
let result: String

if score > 80 {
    result = "great"
} else if score > 60{
  result = "good"  
} else {
    result = "so so..."
}

print(result)

条件演算子

result = score > 80 ? "great" : "soso.."
print(result)

case

let num = 4

switch num {
    case 0:
        print("zero")
    case 1, 2, 3:
        print("small")
    case 4..6:
        print("4/5/6")
    case 7..<9:
        print("7/8")
    case let n where n > 20:
        print("\(n) is huge!")
    default:
        print("n.a.")
}

セミコロンはありません。

print("Hello World!")

Hello World!

自動的に改行されます。

print("Hello World!")
print("Hello")

定数、変数

let msg1: String
msg1 = "this is let"

print(msg1)

var msg2: String
msg2 = "this is variable"
msg2 = "oh, this is swift variable"
print(msg2)

this is let
oh, this is swift variable
なるほど！