Swift enum’lar va pattern matching

Enum’lar va pattern matching

Chekli holatlar to‘plamini enum bilan modellashtiring, bog‘langan qiymatlar (associated values) qo‘shing va switch yordamida andozalar (patterns) bilan solishtiring.

Oddiy enum’lar

Belgilangan holatlar to‘plamiga ega tipni e’lon qilish uchun enum dan foydalaning.

Sintaksis: enum Direction { case north, south, east, west }

enum Direction { case north, south, east, west }

let d: Direction = .east
print(d)

Ushbu misol yo‘nalishlar enum’ini e’lon qiladi va qisqa nuqtali sintaksis yordamida qiymat yaratadi.

Bog‘langan qiymatlar (associated values)

Bog‘langan qiymatlar yordamida har bir holatga ma’lumot biriktiring.

Sintaksis: enum Result { case success(T), failure(Error) }

enum Barcode {
  case upc(Int, Int, Int, Int)
  case qr(String)
}

let b1 = Barcode.upc(8, 85909, 51226, 3)
let b2 = Barcode.qr("HELLO")

Ushbu misolda to‘rtta butun sonli UPC yoki stringli QR kod bo‘lishi mumkin bo‘lgan shtrix-kod ko‘rsatilgan.

Pattern matching (andoza bilan solishtirish)

Bog‘langan qiymatlarni ajratib olish uchun andozalar bilan switch dan foydalaning.

Sintaksis:

• switch value { case .case(let x): ... }
• Bitta holatni tekshirish uchun if case

func describe(_ code: Barcode) {
  switch code {
  case .upc(let numberSystem, let manufacturer, let product, let check):
    print("UPC: \(numberSystem)-\(manufacturer)-\(product)-\(check)")
  case .qr(let text):
    print("QR: \(text)")
  }
}

describe(b1)
describe(b2)

Ushbu misol bog‘langan qiymatlarni bog‘lash uchun pattern matching’dan foydalanadi va formatlangan tavsifni chiqaradi.

Xom qiymatlar (raw values)

Standart xom qiymatlarni (masalan, Int yoki String) belgilang va ulardan initsializatsiya qiling.

Sintaksis:

• enum HTTPStatus: Int { case ok = 200, notFound = 404 }
• HTTPStatus(rawValue: 200)

enum HTTPStatus: Int { case ok = 200, notFound = 404 }

let status = HTTPStatus(rawValue: 200)
print(status == .ok)

Ushbu misol muvaffaqiyatsiz bo‘lishi mumkin bo‘lgan initsializator (failable initializer) yordamida butun sonli holat kodini qayta enum qiymatiga moslaydi.