How does SwiftUI pass EnvironmentObjects between HostingController?

Question

I am trying to implement an Apple Watch app in a similar way as this question: Issues implementing navigation from a main controller to page based controllers in WatchOS using SwiftUI

I am trying to pass data between different HostingControllers. My data is stored in an EnvironmentObject with published properties. If I only use one HostingController, it's fine to share data between the different views. But when using a different HostingController, hosting different views (without segues), I can't find the syntax for using my Environment object from HC1 to HC2, the HC3, etc.

I present the HostingController using this piece of code in my SwiftUI views.

NavigationLink(destinationName: "HC2"){
        Text("Go to HC2")

What approach did you go for in the end? I'm facing the exact same issue. — bencallis
– bencallis, Commented May 16, 2020 at 21:10
I have used this approach which fits my needs. But now, I have another issue. I don't know how to go back to the first HostingController from HC3 or HC4 — Raphaël Barthomeuf
– Raphaël Barthomeuf, Commented May 18, 2020 at 6:02
@bencallis, did you ever find a workable solution for this? I have multiple UIHostingControllers in a navigationcontroller that I want to share data between. — spentag
– spentag, Commented May 26, 2021 at 23:27

Martijn Pieters · Accepted Answer · 2022-08-23 14:58:02Z

3

Here is possible approach

class AppState: ObservableObject {
    static let shared = AppState()      // shared instance

    @Published var setting: String = "some"
}

class HostingController: WKHostingController<AnyView> {
    override var body: AnyView {
        let contentView = ContentView()
            .environmentObject(AppState.shared)     // << inject !!
        return AnyView(contentView)
    }
}

class HostingController2: WKHostingController<AnyView> {
    override var body: AnyView {
        let contentView = ContentView2()
            .environmentObject(AppState.shared)     // << inject !!
        return AnyView(contentView)
    }
}

edited Aug 23, 2022 at 14:58

Martijn Pieters

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answered May 15, 2020 at 10:35

Asperi

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1 Comment

bencallis Over a year ago

Are there any other approaches? Resorting to using global shared data really doesn't seem ideal.

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