println("Hello, world!")
varは変数 letは定数
var myVariable = 42
myVariable = 50
let myConstant = 42
値型は必ずしも明示する必要はない
let implicitInteger = 70
let implicitDouble = 70.0
let explicitDouble: Double = 70
文字列は + で連結
let label = "The width is "
let width = 94
let widthLabel = label + String(width)
文字リテラルで変数・定数を簡単に含める事が可能
let apples = 3
let oranges = 5
let appleSummary = "I have \(apples) apples."
let fruitSummary = "I have \(apples + oranges) pieces of fruit."
配列と辞書
var shoppingList = ["catfish", "water", "tulips", "blue paint"]
shoppingList[1] = "bottle of water"
var occupations = [
"Malcolm": "Captain",
"Kaylee": "Mechanic",
]
occupations["Jayne"] = "Public Relations"
配列と辞書の初期化
let emptyArray = [String]()
let emptyDictionary = [String: Float]()
初期化の短い書き方
shoppingList = []
occupations = [:]
for ループ
let individualScores = [75, 43, 103, 87, 12]
var teamScore = 0
for score in individualScores {
if score > 50 {
teamScore += 3
} else {
teamScore += 1
}
}
println(teamScore)
firstForLoop と secondForLoop は同じ意味のコード
var firstForLoop = 0
for i in 0..<4 {
firstForLoop += i
}
println(firstForLoop)
var secondForLoop = 0
for var i = 0; i < 4; ++i {
secondForLoop += i
}
println(secondForLoop)
オプショナル
var optionalString: String? = "Hello"
println(optionalString == nil)
条件分岐 if の条件指定で let を用いる nil チェックに変わる型安全な判定がswift流
var optionalName: String? = "John Appleseed"
var greeting = "Hello!"
if let name = optionalName {
greeting = "Hello, \(name)"
}
条件分岐 switch
let vegetable = "red pepper"
switch vegetable {
case "celery":
let vegetableComment = "Add some raisins and make ants on a log."
case "cucumber", "watercress":
let vegetableComment = "That would make a good tea sandwich."
case let x where x.hasSuffix("pepper"):
let vegetableComment = "Is it a spicy \(x)?"
default:
let vegetableComment = the"Everything tastes good in soup."
}
辞書と配列による繰り返し
let interestingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 9, 16, 25],
]
var largest = 0
for (kind, numbers) in interestingNumbers {
for number in numbers {
if number > largest {
largest = number
}
}
}
println(largest)
while ループ
var n = 2
while n < 100 {
n = n * 2
}
println(n)
var m = 2
do {
m = m * 2
} while m < 100
println(m)
関数定義
func greet(name: String, day: String) -> String {
return "Hello \(name), today is \(day)."
}
greet("Bob", "Tuesday")
クロージャー
func calculateStatistics(scores: [Int]) -> (min: Int, max: Int, sum: Int) {
var min = scores[0]
var max = scores[0]
var sum = 0
for score in scores {
if score > max {
max = score
} else if score < min {
min = score
}
sum += score
}
return (min, max, sum)
}
let statistics = calculateStatistics([5, 3, 100, 3, 9])
println(statistics.sum)
println(statistics.2)
可変長引数
func sumOf(numbers: Int...) -> Int {
var sum = 0
for number in numbers {
sum += number
}
return sum
}
sumOf()
sumOf(42, 597, 12)
内部関数
func returnFifteen() -> Int {
var y = 10
func add() {
y += 5
}
add()
return y
}
returnFifteen()
返値が関数
func makeIncrementer() -> (Int -> Int) {
func addOne(number: Int) -> Int {
return 1 + number
}
return addOne
}
var increment = makeIncrementer()
increment(7)
引数が関数
func hasAnyMatches(list: [Int], condition: Int -> Bool) -> Bool {
for item in list {
if condition(item) {
return true
}
}
return false
}
func lessThanTen(number: Int) -> Bool {
return number < 10
}
var numbers = [20, 19, 7, 12]
hasAnyMatches(numbers, lessThanTen)
map関数のクロージャー
numbers.map({
(number: Int) -> Int in
let result = 3 * number
return result
})
map関数のクロージャー 短い書き方
let mappedNumbers = numbers.map({ number in 3 * number })
println(mappedNumbers)
引数は$0,$1と表現できる
let sortedNumbers = sorted(numbers) { $0 > $1 }
println(sortedNumbers)
クラス定義
class Shape {
var numberOfSides = 0
func simpleDescription() -> String {
return "A shape with \(numberOfSides) sides."
}
}
インスタンス化
var shape = Shape()
shape.numberOfSides = 7
var shapeDescription = shape.simpleDescription()
クラス定義 イニシャライザー
class NamedShape {
var numberOfSides: Int = 0
var name: String
init(name: String) {
self.name = name
}
func simpleDescription() -> String {
return "A shape with \(numberOfSides) sides."
}
}
クラス定義 継承、イニシャライザー追加、オーバーライド
class Square: NamedShape {
var sideLength: Double
init(sideLength: Double, name: String) {
self.sideLength = sideLength
super.init(name: name)
numberOfSides = 4
}
func area() -> Double {
return sideLength * sideLength
}
override func simpleDescription() -> String {
return "A square with sides of length \(sideLength)."
}
}
let test = Square(sideLength: 5.2, name: "my test square")
test.area()
test.simpleDescription()
クラス定義 継承、プロパティの初期値、アクセッサー
class EquilateralTriangle: NamedShape {
var sideLength: Double = 0.0
init(sideLength: Double, name: String) {
self.sideLength = sideLength
super.init(name: name)
numberOfSides = 3
}
var perimeter: Double {
get {
return 3.0 * sideLength
}
set {
sideLength = newValue / 3.0
}
}
override func simpleDescription() -> String {
return "An equilateral triangle with sides of length \(sideLength)."
}
}
var triangle = EquilateralTriangle(sideLength: 3.1, name: "a triangle")
println(triangle.perimeter)
triangle.perimeter = 9.9
println(triangle.sideLength)
クラス定義 プロパティオブザーバー
class TriangleAndSquare {
var triangle: EquilateralTriangle {
willSet {
square.sideLength = newValue.sideLength
}
}
var square: Square {
willSet {
triangle.sideLength = newValue.sideLength
}
}
init(size: Double, name: String) {
square = Square(sideLength: size, name: name)
triangle = EquilateralTriangle(sideLength: size, name: name)
}
}
var triangleAndSquare = TriangleAndSquare(size: 10, name: "another test shape")
println(triangleAndSquare.square.sideLength)
println(triangleAndSquare.triangle.sideLength)
triangleAndSquare.square = Square(sideLength: 50, name: "larger square")
println(triangleAndSquare.triangle.sideLength)
クラスメソッドの引数が名前を持つ例。引数名を持つ事で読解可能、呼び出しの書き方が自然な英語のように表現出来る。
class Counter {
var count: Int = 0
func incrementBy(amount: Int, numberOfTimes times: Int) {
count += amount * times
}
}
var counter = Counter()
counter.incrementBy(2, numberOfTimes: 7)
オプショナル値の場合、?マークでアンラップしつつメソッドやプロパティにアクセス可能。 nilの際はそのままnilが返る。
let optionalSquare: Square? = Square(sideLength: 2.5, name: "optional square")
let sideLength = optionalSquare?.sideLength
列挙型
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
if let convertedRank = Rank(rawValue: 3) {
let threeDescription = convertedRank.simpleDescription()
}
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"
}
}
}
let hearts = Suit.Hearts
let heartsDescription = hearts.simpleDescription()
構造体
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 threeOfSpadesDescription = threeOfSpades.simpleDescription()
列挙型のcaseは引数を持てる
enum ServerResponse {
case Result(String, String)
case Error(String)
}
let success = ServerResponse.Result("6:00 am", "8:09 pm")
let failure = ServerResponse.Error("Out of cheese.")
switch success {
case let .Result(sunrise, sunset):
let serverResponse = "Sunrise is at \(sunrise) and sunset is at \(sunset)."
case let .Error(error):
let serverResponse = "Failure... \(error)"
}
プロトコル定義とその適用
protocol ExampleProtocol {
var simpleDescription: String { get }
mutating func adjust()
}
class SimpleClass: ExampleProtocol {
var simpleDescription: String = "A very simple class."
var anotherProperty: Int = 69105
func adjust() {
simpleDescription += " Now 100% adjusted."
}
}
var a = SimpleClass()
a.adjust()
let aDescription = a.simpleDescription
struct SimpleStructure: ExampleProtocol {
var simpleDescription: String = "A simple structure"
mutating func adjust() {
simpleDescription += " (adjusted)"
}
}
var b = SimpleStructure()
b.adjust()
let bDescription = b.simpleDescription
エクステンションで直接機能拡張が可能
extension Int: ExampleProtocol {
var simpleDescription: String {
return "The number \(self)"
}
mutating func adjust() {
self += 42
}
}
println(7.simpleDescription)
let protocolValue: ExampleProtocol = a
println(protocolValue.simpleDescription)
// println(protocolValue.anotherProperty) // Uncomment to see the error
ジェネリクスによる抽象化で引数の型を限定しない
func repeat<Item>(item: Item, times: Int) -> [Item] {
var result = [Item]()
for i in 0..<times {
result.append(item)
}
return result
}
repeat("knock", 4)
Swiftスタンダードライブラリーのオプショナル型を再実装
// Reimplement the Swift standard library's optional type
enum OptionalValue<T> {
case None
case Some(T)
}
var possibleInteger: OptionalValue<Int> = .None
possibleInteger = .Some(100)
whereは省略可能で <T where T: Equatable> を <T: Equatable> とできる
func anyCommonElements <T, U where T: SequenceType, U: SequenceType, T.Generator.Element: Equatable, T.Generator.Element == U.Generator.Element> (lhs: T, rhs: U) -> Bool {
for lhsItem in lhs {
for rhsItem in rhs {
if lhsItem == rhsItem {
return true
}
}
}
return false
}
anyCommonElements([1, 2, 3], [3])