如何在 Swiftui View 函数中使用 EnvironmentObject？

Question

Resolved

Finally, I found the problem. My questioned View was placed in a .sheet. If I show this View separately, the environment variables will work, but if they are placed in .sheet, the Store must be explicitly injected in.

.sheet(isPresented: $showEditSheet){
        EditFavoriteRootView().environmentObject(Store())
    }

Now It's worked!

old quesition

Because ForEach couldn't support too complicated logic, I defined a function in the View to implement the content. In most cases, this is fine. However, I cannot use the EnviromentObject in the function。

build success , the button in View body works fine, but when I click button in function got the runtime error:

Fatal error: No ObservableObject of type Store found.
A View.environmentObject(_:) for Store may be missing as an ancestor of this view.: file /BuildRoot/Library/Caches/com.apple.xbs/Sources/Monoceros/Monoceros-

Code sample:

struct FromCategory: View {
    @EnvironmentObject var store:Store

    var body: some View {
        ForEach(AppState.HealthCategoryList.keys.sorted(by: <),id:\.self){
            self.ShowList(categoryId: $0)
        }
        Button(action:{
           self.store.dispatch(.updateFavorite(idName:"test"))
        }){Text("Test")}

    }

    func ShowList(categoryId:String)->some View{

        let metalist = AppState.HealthCategoryList[categoryId]?.metaData?.sortedArray(using: [NSSortDescriptor(key: "idName", ascending: true)]) as! [HealthMetaData]

        return VStack{
            VStack(spacing:10)  {
                ForEach(0..<metalist.count){i in
                    HStack{
                        Text(metalist[i].title!)
                        Spacer()
                        Button(action:{
                            self.store.dispatch(.updateFavorite(idName: metalist[i].idName!))
                            //self.store.appState.updateFavorite(idName: metalist[i].idName!)
                        }){
                            if AppState.UserFavoriteList[metalist[i].idName!] != nil {
                                Image(systemName: "star.fill")
                            }
                            else {
                                Image(systemName: "star")
                            }
                        }
                    }

                }
            }
        }

    }   

}

Fatal error: No ObservableObject of type Store found. in this line

self.store.dispatch(.updateFavorite(idName: metalist[i].idName!))

store can be use well in normal some View, but not in function. How to solve this. Or is there any other way? Thanks

Answer 1

This is happening because you want to update an EnvironmentObject and you're not in the View which was loaded by the SceneDelegate.swift

In case you're using the EnvObject in a correct way, you just need to pass te EnvObject to the next view like this:

DestinationView().environmentObject(self.yourEnvObject)

More information explained in my post: https://stackoverflow.com/a/58997326/12378791