ios - 设置 userActivity 时，我们是否必须覆盖 updateUserActivityState

Question

关于 updateUserActivityState 的文档对我来说有点模糊。

https://developer.apple.com/documentation/uikit/uiresponder/1621095-updateuseractivitystate

Subclasses override this method to update the state of the given user activity. You should add state representing the user's activity into the NSUserActivity object using its addUserInfoEntries(from:) method.

When the state is dirty, you should set the needsSave property of the NSUserActivity to true, and this method will be called at an appropriate time.

所以这个方法在我们做的时候被调用:

open override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    self.userActivity?.needsSave = true
}

然后我们可以相应地更新事件:

override func updateUserActivityState(activity: NSUserActivity) {

  activity.addUserInfoEntriesFromDictionary(someInfo)
  super.updateUserActivityState(activity)
}

但是当我们只设置一次事件并且永远不会更新它时，我们是否也必须始终实现 updateUserActivityState？

例如在 viewDidLoad 中设置一次事件时:

override open func viewDidLoad() {
    super.viewDidLoad()

    let activity = NSUserActivity(activityType: "com.myApp")
    activity.title = "Viewing"
    activity.userInfo = ["myApp.item.key": ["Some", "Things"]]
    self.userActivity = activity
    self.userActivity?.becomeCurrent()
}

Answer 1

But when we only set the activity once and never update it, should we also always have to implement updateUserActivityState?

如果 NSUserActivity 对象永远不会改变，并且在创建时已完全配置，则无需重写 UIResponder.updateUserActivityState 方法。

但是，为了保持一致性和面向 future (如果您确实使该用户事件对象可变)，当响应者链收到更改通知时，应用可能仍希望使用 updateUserActivityState 来填充事件。