如何按属性名称设置 Swift 值？

Question

Objective-C 有一种setValue方法允许开发人员通过字段名称为字段设置特定值。

我如何在 Swift 中做到这一点而不继承 NSObject 并实际使用该setValue方法？

Answer 1

你可以使用 KVC 来做到这一点，据我所知。看看这个很酷的例子： https://www.raywenderlich.com/163857/whats-new-swift-4

struct Lightsaber {
  enum Color {
    case blue, green, red
  }
  let color: Color
}

class ForceUser {
  var name: String
  var lightsaber: Lightsaber
  var master: ForceUser?

  init(name: String, lightsaber: Lightsaber, master: ForceUser? = nil) {
    self.name = name
    self.lightsaber = lightsaber
    self.master = master
  }
}

let sidious = ForceUser(name: "Darth Sidious", lightsaber: Lightsaber(color: .red))
let obiwan = ForceUser(name: "Obi-Wan Kenobi", lightsaber: Lightsaber(color: .blue))
let anakin = ForceUser(name: "Anakin Skywalker", lightsaber: Lightsaber(color: .blue), master: obiwan)

// Use keypath directly inline and to drill down to sub objects
let anakinSaberColor = anakin[keyPath: \ForceUser.lightsaber.color]  // blue

// Access a property on the object returned by key path
let masterKeyPath = \ForceUser.master
let anakinMasterName = anakin[keyPath: masterKeyPath]?.name  // "Obi-Wan Kenobi"

// AND HERE's YOUR ANSWER
// Change Anakin to the dark side using key path as a setter
anakin[keyPath: masterKeyPath] = sidious
anakin.master?.name // Darth Sidious