How to resolve 'Missing argument for parameter 'realmManager' in call' error for TasksView() in Realm?

Question

获取 TasksView() 的“调用中缺少参数‘realmManager’的参数”错误

我尝试阅读 Realm 的文档，但根据代码，我认为没有任何问题？有东西不见了，但我不知道它是什么。

代码如下：

TasksView 文件 -

import SwiftUI

struct TasksView: View {
    @Environment var realmManager: RealmManager
    var body: some View {
        VStack {
            Text("Task List")
                .font(.title3).bold()
                .padding()
                .frame(maxWidth: .infinity, alignment: .leading)
            
            
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(Color(hue: 0.086, saturation: 0.141, brightness: 0.901))
    }
}

struct TasksView_Previews: PreviewProvider {
    static var previews: some View {
        TasksView()
            .environmentObject(realmManager)
        
          
    }
}

ContentView2 文件 -

import SwiftUI

struct ContentView2: View {
    @StateObject var realmManager = RealmManager()
    @State private var showAddTaskView = false
    
    
    var body: some View {
        ZStack(alignment: .bottomTrailing){
            TasksView()
                .environmentObject(realmManager)
            
            SmallAddButton()
                .padding()
                .onTapGesture {
                    showAddTaskView.toggle()
                }
            
            
        }
        .sheet(isPresented: $showAddTaskView) {
            AddTaskView()
                .environmentObject(realmManager)

            
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .bottom)
        .background(Color(hue: 0.086, saturation: 0.141, brightness: 0.901))
    }
}

struct ContentView2_Previews: PreviewProvider {
    static var previews: some View {
        ContentView2()
    }
}

Answer 1

@Environment

与

environment

视图修饰符一起使用，并允许您读取

EnvironmentValues

的特定键路径的值。

你正在使用

environmentObject

来注入领域管理器，因为你想在视图之间共享领域管理器。您应该使用

@EnvironmentObject

来读取

environmentObject

修饰符的值，而不是

@Environment

.

像这样声明

realmManager

：

@EnvironmentObject var realmManager: RealmManager

Answer 2

我认为问题出在您在

realmManager

中的

TaskView

声明中。每当您通过

@StateObject

将

environmentObject(_:)

传递给视图层次结构时，您在子视图中使用该对象的方式是用

@EnvironmentObject

包装一个变量，该变量具有您想要使用的所需对象类型，而不是

@Environment 

.每种类型只能有一个环境对象，允许 SwiftUI 推断您的

@EnvironmentObject

正在引用哪个对象。

例子：

@main
struct MemorizeApp: App {
    // Create @StateObject
    @StateObject var themeStore = ThemeStore()

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(themeStore)
                // Allow this same @StateObject to be used in all child views of
                // ContentView, and ContentView itself, as an @EnvironmentObject.
        }
    }
}

struct ContentView: View {
    // Don't need our @EnvironmentObject here
    // yet, so we don't declare anything.
    var body: some View {
        ThemeChooser()
    }
}

struct ThemeChooser: View {
    // ThemeChooser is a descendent of ContentView and thus we
    // can use our @EnvironmentObject of type ThemeStore here.
    @EnvironmentObject var store: ThemeStore
    
    var body: some View {
        List {
            ForEach(store.themes) { theme in
                Text(theme)
                // More logic ...
            }
        }
    }
}

@Environment

用于不同的目的，可以阅读更多信息here.