Leistungsfähiges switch mit Pattern Matching

Warum Pattern Matching?

Zugehörige Werte

enum Network {
    case success(code: Int, body: String)
    case failure(message: String)
    case offline
}

let r1: Network = .success(code: 200, body: "OK")
switch r1 {
case .success(let code, let body):
    print("success", code, body)
case .failure(let msg):
    print("fail:", msg)
case .offline:
    print("offline")
}

Bereichsabgleich

let score = 73
switch score {
case 90...100:
    print("A")
case 80..<90:
    print("B")
case 60..<80:
    print("C")
case 0..<60:
    print("D")
default:
    print("invalid")
}

Tupel und where

let point = (x: -2, y: 3)
switch point {
case (0, 0):
    print("origin")
case (let x, 0):
    print("x-axis at", x)
case (0, let y):
    print("y-axis at", y)
case (let x, let y) where x > 0 && y > 0:
    print("Q1:", x, y)
default:
    print("somewhere else")
}

Platzhalter und Teilübereinstimmungen

enum Event {
    case message(String, priority: Int)
    case ping
}
let e: Event = .message("update", priority: 1)

switch e {
case .message(let text, priority: _):
    print("msg:", text)           // ignore priority with _
case .ping:
    print("ping")
}

Tipps

Die Leistungsfähigkeit von switch

Zusammenfassung