Swift UI 更新@EnvironmentObject 防止@StateObject

问题描述

我有以下视图 ModalView 由父视图 ParentView 使用工具栏中的按钮打开

** 父视图 **

import SwiftUI

struct ParentView: View {
    
    @EnvironmentObject var environmentObject: MainStore
    @State private var showCreationView = false
    
    var body: some View {
        NavigationView {
            Text("ENV_OBJ Count: \(environmentObject.shoppingChartFullList.count)")
            .navigationBarTitle(Text("Navigation Bar Title"))
            .toolbar {
                ToolbarItem(placement: .bottomBar) {
                    Button(action: { showCreationView = true }) {
                        Image(systemName: "plus")
                    }
                    
                    .sheet(isPresented: $showCreationView,content: {
                        ModalView(showModelView: $showCreationView)
                    })
                }
            }
        }
    }
}

struct ParentView_Previews: PreviewProvider {
    static var previews: some View {
        ParentView().environmentObject(MainStore())
    }
}

** 模态视图 **

import SwiftUI

struct ModalView: View {
    
    @EnvironmentObject var environmentObject: MainStore
    @Binding var showModelView: Bool
    
    @State var newItem = ShoppingChartModel()
    
    var body: some View {
        Text(/*@START_MENU_TOKEN@*/"Hello,World!"/*@END_MENU_TOKEN@*/)
        Button(action: {
            
            environmentObject.shoppingChartFullList.append(newItem)
            self.showModelView = false

          }) {Text("Salva")}
    }
}

struct ModalView_Previews: PreviewProvider {
    static var previews: some View {
        ModalView(showModelView: .constant(true)).environmentObject(MainStore())
    }
}

** 总店 **

import Foundation
import SwiftUI
import Combine

final class MainStore: ObservableObject {
    //An observable object needs to publish any changes to its data,so that its subscribers can pick up the change.
    @Published var shoppingChartFullList: [ShoppingChartModel] = load()
}

问题在于，由模态视图中的保存按钮执行的操作不会关闭模态（即使它正确更新了布尔变量和 Env_Obj）。

似乎和工具栏有关...其实如果我把导航视图和工具栏去掉，把按钮直接放在一个堆栈里...就可以了...

在 Parent2View 中，我删除了 NavigationView 并在 Text 属性之后直接在视图中配置了按钮。它按预期工作。

import SwiftUI

struct ParentView2: View {
    
    @EnvironmentObject var environmentObject: MainStore
    @State private var showCreationView = false
    
    var body: some View {
        vstack {
            Text("ENV_OBJ Count: \(environmentObject.shoppingChartFullList.count)")
            Button(action: { showCreationView = true }) {
                Image(systemName: "plus")
            }
            .sheet(isPresented: $showCreationView,content: {
                ModalView(showModelView: $showCreationView)
            })
        }
    }
}

struct ParentView2_Previews: PreviewProvider {
    static var previews: some View {
        ParentView2().environmentObject(MainStore())
    }
}

更新 好的，我终于找到了解决方案。问题是工具栏。如果 ParentView 修改如下，一切都开始正常运行

struct ParentView: View {
    
    @EnvironmentObject var environmentObject: MainStore
    @State private var showCreationView = false
    
    var body: some View {
        NavigationView {
            Text("ENV_OBJ Count: \(environmentObject.shoppingChartFullList.count)")
            .navigationBarTitle("Nav View Title")
            .navigationBarItems(trailing:
                Button(action: {
                    self.showCreationView.toggle()
                })
                {
                    Image(systemName: "plus")
                        .font(Font.system(.title))
                }
            )
        }
        .sheet(isPresented: $showCreationView) {
                    ModalView(showModelView: $showCreationView)
                }
    }
}

谢谢！ 克里斯蒂安

解决方法

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