SwiftUI中的EnvironmentObject vs Singleton? [英] EnvironmentObject vs Singleton in SwiftUI?

问题描述

如果整个视图在应用程序中访问同一模型，则我认为Singleton模式就足够了.我说的对吗?

If the entire views access the same model in an app, I think the Singleton pattern is enough. Am I right?

例如，如果MainView和ChildView访问相同的模型(例如AppSetting)，如下所示，我找不到使用EnvironmentObject而不是Singleton模式的任何理由. 如果我这样使用是否有问题?如果可以，那么什么时候应该使用EnvironmentObject而不是Singleton模式?

For example, if MainView and ChildView access the same model(e.g. AppSetting) like below, I cannot find any reason to use EnvironmentObject instead of the Singleton pattern. Is there any problem if I use like this? If it is okay, then when I should use EnvironmentObject instead of the Singleton pattern?

class AppSetting: ObservableObject {
    static let shared = AppSetting()
    private init() {}

    @Published var userName: String = "StackOverflow"
}

struct MainView: View {
    @ObservedObject private var appSetting = AppSetting.shared

    var body: some View {
        Text(appSetting.userName)
    }
}

struct ChildView: View {
    @ObservedObject private var appSetting = AppSetting.shared

    var body: some View {
        Text(appSetting.userName)
    }
}

谢谢.

推荐答案

您是正确的，在这种情况下没有理由使用EnvironmentObject.苹果甚至鼓励不要过度使用EnvironmentObject.

You are correct there is no reason in this case to use an EnvironmentObject. Apple even encourages to make no excessive use of EnvironmentObject.

尽管如此，如果您在多个视图中使用对象，EnvironmentObject也可以很棒，因为这样您就不必将其从视图A传递到视图B，从视图B传递到视图C，依此类推.

Nevertheless EnvironmentObject can be great too, if you use an object in many views, because then you don't have to pass it from View A to B, from B to C and so on.

通常您会发现自己处于这样一种情况，即使@State和@Binding也足以在一个视图中以及两个视图之间共享和更新数据.

Often you find yourself in a situation where even @State and @Binding will be enough to share and update data in a view and between two views.

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