SwiftUI发布的更新不刷新 [英] SwiftUI Published updates not refreshing

问题描述

我正在尝试通过一系列嵌套的类来管理用户状态.

I'm trying to manage user state via a series of nested classes.

应用程序的基本视图使用 globalState 环境对象.该对象允许用户向内和向外查看其他视图.

The basic view of the app uses a globalState environment object. This object allows other views to the user in and out.

@EnvironmentObject var globalState: GlobalState

// View Code
Text("Logged In").opacity(globalState.user.isLoggedIn ? 1 : 0)
Text("Please Sign In").opacity(globalState.user.isLoggedIn ? 0 : 1)

然后， GlobalState 类仅容纳 User 类. user 字段在其他地方初始化(不，我没有引用其他 user 对象).

Then the GlobalState class merely houses the User class. The user field is init'ed elsewhere (and no, I'm not referencing different user objects).

class GlobalState: ObservableObject {
    @Published public var user: User // Inited somewhere else
}
class User {
    @Published var isLoggedIn: Bool = false
}

User 类在 init 初始化后自动提取有关用户的数据.在应用启动时，从钥匙串(如果有)中提取用户信息.如果可以从现有数据创建用户，则将该用户的 isLoggedIn 设置为 true .

The User class automatically pulls data about the user when it is inited. On app launch, user information is pulled from the Keychain (if present). If the user can be created from existing data, that user's isLoggedIn is set to true.

我知道我没有重复的对象，因为 globalState 的查看代码中 globalState.user 的内存地址与 isLoggedIn时的内存地址相同已为用户更新.

I know I do not have duplicate objects, as the memory addresses of the globalState.user in GlobalState's View Code is the same as when isLoggedIn is updated for a user.

通过使用两个级别的 @Published 变量，我对部队产生了干扰，但是一切应该解决吗?

I feel a disturbance in the Force by using two levels of @Published variables, but everything should work out?

GlobalState 中的视图代码虽然不会更新.有人知道为什么吗?我缺少一些柔术柔术?

The view code in GlobalState does not update though. Any one know why? Some Combine jiu jitsu I'm missing?

推荐答案

@Published 发布值更改，因此，如果要替换User对象，它将进行更新.由于User是类(引用类型)，因此当User.isLoggedIn更改时，它将不会更新GlobalState.user的值.

@Published publishes value changes, so if you would replace the User object it would update. Since User is a class (Reference type) it will not update the value of GlobalState.user when User.isLoggedIn changes.

此问题的解决方法是此名为NestedPublished的程序包，该程序包将嵌套的ObservableObject.willChange发送给其父级.

Fix for this is this package called NestedPublished which sends the nested ObservableObject.willChange to its parent.

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