Question

我在导航视图堆栈的屏幕上的窗体中嵌入了一个选择器。我已经重新创建了一个简单的版本。

struct ContentView: View {
    
    @State var showSecondView: Bool = false
    
    var body: some View {
        NavigationView {
            VStack {
                Button("SecondView", action: {
                    self.showSecondView = true
                })
                NavigationLink(destination: SecondContentView(), isActive: $showSecondView) {
                    EmptyView()
                }
            }
        }
        
    }
}

struct SecondContentView: View {
    
    @State var showThirdView: Bool = false
    
    var body: some View {
            VStack {
                Button("ThirdView", action: {
                    self.showThirdView = true
                })
                NavigationLink(destination: ThirdContentView(showThirdView: $showThirdView), isActive: $showThirdView) {
                    EmptyView()
                }
            }
    }
}

struct ThirdContentView: View {
    
    @Binding var showThirdView: Bool
    @State var pickerSelection: String = ""
    let pickerObjects = ["A", "B", "C"]
    
    var body: some View {
            VStack {
                Form {
                    Picker(selection: $pickerSelection, label: Text("Abort Reason")
                    ) {
                        ForEach(0 ..< pickerObjects.count) { i in
                            Text("\(self.pickerObjects[i])").tag(self.pickerObjects[i])
                        }
                    }
                }
                Button("Done", action: {
                    self.showThirdView.toggle()
                })
            }
    }
}

在上面的示例中，当我设置一个值并按完成时，它导航回到第三个屏幕（带有选择器），但未选择任何值。在我的完整应用程序中，完成按钮可关闭第三个屏幕，但是当我在第二个屏幕上按回去时，它会短暂显示第三个屏幕一秒钟，然后再将其关闭。

如果我在导航链接之外显示第三个视图（如果showThirdView == true），则没有导航错误。在选择器中设置一个值似乎会将第三个视图的另一个实例添加到NavigationView堆栈中，而不是返回。我喜欢导航链接样式，因为后退按钮对用户而言是一致的。有什么方法可以使选择器在导航链接中工作？

Answer 1

这是起作用的固定部件-用演示文稿模式替换了丢失的Binding。在Xcode 12 / iOS 14上进行了测试。

struct SecondContentView: View {
    @State var showThirdView: Bool = false

    var body: some View {
            VStack {
                Button("ThirdView", action: {
                    self.showThirdView = true
                })
                NavigationLink(destination: ThirdContentView(), isActive: $showThirdView) {
                    EmptyView()
                }
            }
    }
}

struct ThirdContentView: View {
    @Environment(\.presentationMode) var mode

    @State var pickerSelection: String = ""
    let pickerObjects = ["A", "B", "C"]

    var body: some View {
            VStack {
                Form {
                    Picker(selection: $pickerSelection, label: Text("Abort Reason")
                    ) {
                        ForEach(0 ..< pickerObjects.count) { i in
                            Text("\(self.pickerObjects[i])").tag(self.pickerObjects[i])
                        }
                    }
                }
                Button("Done", action: {
                    self.mode.wrappedValue.dismiss()
                })
            }
    }
}

导航链接中的选择器选择导致异常行为

1 个答案: