swift がいまいちイケてない 10 のコト

Swift のイケてるとこ

イケてるとこ• No more too many @s!

• No more YES / NO !

• No more [brackets forMethodCall] !

• Type Inference, Closures, Generics, Operator Overloading, …

let view: UIView = … view.frame.origin.x = 100 // hooray, no error!!!

I love this one.

Objective-C だとこうなってた

UIView *view = … ; view.frame.origin.x = 100;

NOTE !“Unlike Objective-C, Swift enables you to set sub-properties of a structure property directly. ” !Apple Inc. “The Swift Programming Language”。 iBooks. https://itun.es/jp/jEUH0.l

YES!

https://itun.es/jp/jEUH0.l

イケてないとこ

その1. public, private などがない7/22 beta4 で対応!

その1. public, private などがない

class Hoge { public let a = 1 private var b = 2 }

その2. class-var がない


“not yet” supported とな

class Hoge { class let a = 1 class var b = 2 }


※ computed class-property がそれっぽく使える

class Hoge { class var hoge: String { return "hoge" } } !println(Hoge.hoge) // "hoge"


※ struct は、stored / computed 共にいける

struct Hoge { static var hoge = "hoge" static var fuga: String { return "fuga" } } !println(Hoge.hoge) println(Hoge.fuga)

その3. optional-binding の構文がいまいち


何やってるか分かります？

let intString = "1024" let maybeInt = intString.toInt() !if let actualInt = maybeInt { println(actualInt) // 1,024 } else { println("\(intString) not an Int expression.") }


これと同じ

let intString = "1024" let maybeInt: Int? = intString.toInt() // optional !if maybeInt { let actualInt: Int = maybeInt! // unwrap println(actualInt) // 1,024 } else { println("\(intString) not an Int expression.") }

その4. func / init / method での named-parameter の違い


func の場合、引数をカンマ区切りで

func add(a: Int, b: Int, c: Int) -> Int { return a + b + c; } !add(1, 2, 3) // 6


init の場合、named-parameter を指定する

class Hoge { let result: Int init(a: Int, b: Int, c: Int) { result = a + b + c } } !let hoge = Hoge(a: 1, b: 2, c: 3) hoge.result // 6


method の場合、 2番目以降の named-parameter を指定する (WTF!?!?!??)

class Hoge { func add(a: Int, b: Int, c: Int) -> Int { return a + b + c; } } !let hoge = Hoge() hoge.add(1, b: 2, c: 3) // 6


class Hoge { func addWithA(a: Int, b: Int, c: Int) -> Int { return a + b + c; } } !let hoge = Hoge() hoge.addWithA(1, b: 2, c: 3) // 6

こうしろということか…


class Hoge { func add(#a: Int, b: Int, c: Int) -> Int { return a + b + c; } } !let hoge = Hoge() hoge.add(a: 1, b: 2, c: 3) // 6

※ 最初のパラメータも # をつけて指定必須にできる


class Hoge { func add(_ a: Int, _ b: Int, _ c: Int) -> Int { return a + b + c; } } !let hoge = Hoge() hoge.add(1, 2, 3) // 6

※ _ をつけて、指定させないようにもできる


class Hoge { func add(#a: Int, b: Int, c: Int) -> Int { return a + b + c; } } !let hoge = Hoge() hoge.add(b: 2, c: 3, a: 1)

順番は変えられない…

Obj-C 先輩への遠慮が伺える

その5. UIKit binding が中途半端


initWith… は全部 init に統一されている（これはGOOD!）

class UIColor : NSObject, NSSecureCoding, NSCoding, NSCopying { // Initializers for creating non-autoreleased colors init(white: CGFloat, alpha: CGFloat) init(hue: CGFloat, saturation: CGFloat, brightness: CGFloat, alpha: CGFloat) init(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) init(CGColor cgColor: CGColor!) init(patternImage image: UIImage!) init(CIColor ciColor: CIColor!) …


let color1 = UIColor(red: 1.0, green: 0.5, blue: 0.8, alpha: 1.0) let color2 = UIColor(hue: 1.0, saturation: 0.25, brightness: 0.5, alpha: 1.0)

インスタンス化がとても直観的


let color = UIColor(red: 1.0, green: 0.5, blue: 0.8, alpha: 1.0) !var red = 0.0, green = 0.0, blue = 0.0, alpha = 0.0; !color.getRed(&red, green: &green, blue: &blue, alpha: &alpha) !println("red: \(red)") // red: 1.0 println(“green: \(green)") // green: 0.5 println("blue: \(blue)") // blue: 0.8 println(“alpha: \(alpha)") // alpha: 1.0

しかしこれは…


let color = UIColor(red: 1.0, green: 0.5, blue: 0.8, alpha: 1.0) !var red = 0.0, green = 0.0, blue = 0.0, alpha = 0.0; !color.getRed(&red, green: &green, blue: &blue, alpha: &alpha) !println("red: \(red)") // red: 1.0 println(“green: \(green)") // green: 0.5 println("blue: \(blue)") // blue: 0.8 println(“alpha: \(alpha)") // alpha: 1.0

getRed してるようにしか見えない…


let color = UIColor(red: 1.0, green: 0.5, blue: 0.8, alpha: 1.0) !var red = 0.0, green = 0.0, blue = 0.0, alpha = 0.0; !color.getComponents(red: &red, green: &green, blue: &blue, alpha: &alpha) !println("red: \(red)") // red: 1.0 println(“green: \(green)") // green: 0.5 println("blue: \(blue)") // blue: 0.8 println(“alpha: \(alpha)") // alpha: 1.0

こうして頂きたかった。


class NSString { func substringFromIndex(from: Int) -> String! func substringToIndex(to: Int) -> String! func substringWithRange(range: NSRange) -> String! …

From, To, With を一掃して欲しかった。

class NSString { func substring(#from: Int) -> String! func substring(#to: Int) -> String! func substring(#range: NSRange) -> String! …

そういえば名前空間って…


import UIKit !let tableView = UIKit.UITableView()

うーん、そういうことか…


import UIKit !let tableView = UIKit.UITableView()

こうだったらよかったのに…

その6. let な Array は immutable じゃないの？

7/8 beta3 で改善!



Mutability of Collections !Arrays and dictionaries store multiple values together in a single collection. If you create an array or a dictionary and assign it to a variable, the collection that is created will be mutable. This means that you can change (or mutate) the size of the collection after it is created by adding more items to the collection, or by removing existing items from the ones it already contains. Conversely, if you assign an array or a dictionary to a constant, that array or dictionary is immutable, and its size cannot be changed. !Apple Inc. “The Swift Programming Language”。 iBooks. https://itun.es/jp/jEUH0.l

let は immutable, var は mutable.



あれ？

let array = [1, 2, 3] array[0] = 100 println(array) // [100, 2, 3] ...?


append / insert / remove はできない…

let array = [1, 2, 3] array.append(4) array.insert(0, atIndex: 0) array.removeAtIndex(0)


let な Dictionary は厳密に immutable なのだが…

let dic = ["a": "Apple", "b": "Banana"] !dic["a"] = "Apricot" dic.removeValueForKey("a")


なぜか変えれる

let array = [1, 2, 3] array[0] = 100 println(array) // [100, 2, 3] ...?


えー。

“Immutability has a slightly different meaning for arrays, however. You are still not allowed to perform any action that has the potential to change the size of an immutable array, but you are allowed to set a new value for an existing index in the array. This enables Swift’s Array type to provide optimal performance for array operations when the size of an array is fixed.” !Apple Inc. “The Swift Programming Language”。 iBooks. https://itun.es/jp/jEUH0.l


その7. Array は Struct じゃないの？7/8 beta3 で改善!

Structures and Enumerations Are Value Types !A value type is a type that is copied when it is assigned to a variable or constant, or when it is passed to a function. … All of the basic types in Swift̶integers, floating-point numbers, Booleans, strings, arrays and dictionaries̶are value types, and are implemented as structures behind the scenes. !Apple Inc. “The Swift Programming Language”。 iBooks. https://itun.es/jp/jEUH0.l

Arrays are copied. (三段論法)

その7. Array は Struct じゃないの？


あれ？コピーされてないやん…

var array1 = [1, 2, 3, 4] var array2 = array1 !array1[0] = 100 !println(array1) // [100, 2, 3, 4] println(array2) // [100, 2, 3, 4] !?


Dictionary の場合はちゃんとコピーされてる

var dic1 = ["a": "Apple", "b": "Banana"] var dic2 = dic1 !dic1["a"] = "Apricot" !println(dic1) // ["a": "Apricot", "b": "Banana"] println(dic2) // ["a": "Apple", "b": “Banana"]


Assignment and Copy Behavior for Collection Types

Swift’s Array and Dictionary types are implemented as structures. However, arrays have slightly different copying behavior from dictionaries and other structures when they are assigned to a constant or variable, and when they are passed to a function or method. … For arrays, copying only takes place when you perform an action that has the potential to modify the length of the array. !抜粋：Apple Inc. “The Swift Programming Language”。 iBooks. https://itun.es/jp/jEUH0.l

Arrays are different.（開き直り）



長さが変わるときだけコピーされる…

var array1 = [1, 2, 3, 4] var array2 = array1 !array1.append(5) !println(array1) // [1, 2, 3, 4, 5] println(array2) // [1, 2, 3, 4]


unshare() で参照を切り離せる…

var array1 = [1, 2, 3, 4] var array2 = array1 !array1.unshare() array1[0] = 100 !println(array1) // [100, 2, 3, 4] println(array2) // [1, 2, 3, 4]

あと３つ、イケてないってほどでもないけど気になったこと

8. performSelector: 系が一通り使えない

9. KVO がない（今のところ）

10. C++ を直接使えない（C / Obj-C を経由しなきゃいけない）

それ以外のことはだいたいイケてる

今後の進化に期待しましょう

Thanks!

swift がいまいちイケてない 10 のコト

Software

func substring

tableview

uikit binding

array immutable

color uicolor

int expression

int return

string return