SwiftUI-ObservableObject、EnvironmentObject、SummaryView

创建代码后，我想创建一个摘要视图，允许我查看在选择器中选择的值。 我该怎么办？我读了一些关于@observeObject和@EnvironmentObject的论坛，但我不明白。。。 非常感谢：）

---

您可以将您的

@State

属性移动到

可观察对象

：

class ViewModel: ObservableObject {
    @Published var firstAnimal = Animal.allCases[0]
    @Published var secondAnimal = Animal.allCases[0]
}

struct ContentView: View {
    @EnvironmentObject var viewModel: ViewModel
    
    var body: some View {
        ...
        Picker(selection: $viewModel.firstAnimal, label: Text("Select first animal")) {
            ForEach(Animal.allCases, id: \.self) { element in
                Text(element.rawValue.capitalized)
            }
        }
    }
}

并从

@EnvironmentObject

访问它们：

class ViewModel: ObservableObject {
    @Published var firstAnimal = Animal.allCases[0]
    @Published var secondAnimal = Animal.allCases[0]
}

struct ContentView: View {
    @EnvironmentObject var viewModel: ViewModel
    
    var body: some View {
        ...
        Picker(selection: $viewModel.firstAnimal, label: Text("Select first animal")) {
            ForEach(Animal.allCases, id: \.self) { element in
                Text(element.rawValue.capitalized)
            }
        }
    }
}

记住将

ViewModel

插入到根视图：

ContentView().environmentObject(ViewModel())

---

您可以将您的

@State

属性移动到

可观察对象

：

class ViewModel: ObservableObject {
    @Published var firstAnimal = Animal.allCases[0]
    @Published var secondAnimal = Animal.allCases[0]
}

struct ContentView: View {
    @EnvironmentObject var viewModel: ViewModel
    
    var body: some View {
        ...
        Picker(selection: $viewModel.firstAnimal, label: Text("Select first animal")) {
            ForEach(Animal.allCases, id: \.self) { element in
                Text(element.rawValue.capitalized)
            }
        }
    }
}

并从

@EnvironmentObject

访问它们：

class ViewModel: ObservableObject {
    @Published var firstAnimal = Animal.allCases[0]
    @Published var secondAnimal = Animal.allCases[0]
}

struct ContentView: View {
    @EnvironmentObject var viewModel: ViewModel
    
    var body: some View {
        ...
        Picker(selection: $viewModel.firstAnimal, label: Text("Select first animal")) {
            ForEach(Animal.allCases, id: \.self) { element in
                Text(element.rawValue.capitalized)
            }
        }
    }
}

记住将

ViewModel

插入到根视图：

ContentView().environmentObject(ViewModel())