swift 通过枚举匹配的可选值（模式）

Posted 2021-05-19

import Foundation

let x: String? = nil
let y: String? = "Hello Y"

switch (x,y) {
    case (.some(let a), .some(let b)):
        print("So \(a) and \(b)")
    case (.none, .none):
        print("None")
    case (.none, .some(let a)):
        print("One val \(a)")
    default:
        print("default")
}

// same can be written as when we need both to be non nil.

switch (x, y) {
    case let (a?, b?):
        print("So \(a) and \(b)")
    default:
        print("default")
}