Swift 3自定义扩展ns测量？防爆。绵羊到山羊

Question

在ns测量中自定义绵羊到山羊的转换？

如何将swift的测量库扩展到自定义转换单位？

示例是我想将绵羊转换为山羊。

Answer 1

请参阅https://developer.apple.com/reference/foundation/nsdimension

示例实施：

class Animal : Dimension {
    static let sheep = Animal(symbol: "Sh", converter: UnitConverterLinear(coefficient: 2.0))
    static let goat = Animal(symbol: "Go", converter: UnitConverterLinear(coefficient: 1.0))
    static let elephant = Animal(symbol: "El", converter: UnitConverterLinear(coefficient: 100.0))

    override class func baseUnit() -> Animal {
        return Animal.goat
    }
}

var x = Measurement(value:5, unit: Animal.sheep) // 5.0 Sh
x.convert(to: Animal.goat) // 10.0 Go
x.convert(to: Animal.elephant) // 0.1 El