SwiftUI - How to close the sheet view, while dismissing that view

问题

I want to achieve the function. Like, "Look up" view that is from Apple.

My aim is when the sheet view push another view by navigation, the user can tap the navigation item button to close the sheet view. Like, this below gif.

I try to achieve this function.

I found a problem that is when the user tap the "Done" button. The App doesn't close the sheet view. It only pop the view to parent view. Like, this below gif.

This is my code.

import SwiftUI

struct ContentView: View {
    @State var isShowSheet = false
    var body: some View {
        Button(action: {
            self.isShowSheet.toggle()
        }) {
            Text("Tap to show the sheet")
        }.sheet(isPresented: $isShowSheet) {
            NavView()
        }
    }
}

struct NavView: View {
    var body: some View {
        NavigationView {
            NavigationLink(destination: NavSubView()) {
                Text("Enter Sub View")
            }
        } .navigationViewStyle(StackNavigationViewStyle())
    }
}

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

    var body: some View {
        Text("Hello")
        .navigationBarItems(trailing:
            Button(action: {
                self.presentationMode.wrappedValue.dismiss()
            }){
                Text("Done")
            }
        )
    }
}

How did I achieve this function? :) Please help me, thank you. :)

回答1:

As navigation in sheet might be long enough and closing can be not in all navigation subviews, I prefer to use environment to have ability to specify closing feature only in needed places instead of passing binding via all navigation stack.

Here is possible approach (tested with Xcode 11.2 / iOS 13.2)

1) Define environment key to store sheet state

struct ShowingSheetKey: EnvironmentKey {
    static let defaultValue: Binding<Bool>? = nil
}

extension EnvironmentValues {
    var showingSheet: Binding<Bool>? {
        get { self[ShowingSheetKey.self] }
        set { self[ShowingSheetKey.self] = newValue }
    }
}

2) Set this environment value to root of sheet content, so it will be available in any subview when declared

    }.sheet(isPresented: $isShowSheet) {
        NavView()
           .environment(\.showingSheet, self.$isShowSheet)
    }

3) Declare & use environment value only in subview where it is going to be used

struct NavSubView: View {
    @Environment(\.showingSheet) var showingSheet

    var body: some View {
        Text("Hello")
        .navigationBarItems(trailing:
            Button("Done") {
                self.showingSheet?.wrappedValue = false
            }
        )
    }
}

回答2:

I haven't tried SwiftUI ever, but I came from UIKit + RxSwift, so I kinda know how binding works. I read quite a bit of sample codes from a SwiftUI Tutorial, and the way you dismiss a modal is actually correct, but apparently not for a navigation stack.

One way I learned just now is use a @Binding var. This might not be the best solution, but it worked!

So you have this $isShowSheet in your ContentView. Pass that object to your NavView struct by declaring a variable in that NavView.

ContentView

    .....

    }.sheet(isPresented: $isShowSheet) {
        NavView(isShowSheet: self.$isShowSheet)
    }

NavView

struct NavView: View {
    @Binding var isShowSheet: Bool

    var body: some View {
        NavigationView {
            NavigationLink(destination: NavSubView(isShowSheet: self.$isShowSheet)) {
                Text("Enter Sub View")
            }
        } .navigationViewStyle(StackNavigationViewStyle())
    }
}

and finally, do the same thing to your subView.

NavSubView

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

    @Binding var isShowSheet: Bool

    var body: some View {
        Text("Hello")
        .navigationBarItems(trailing:
            Button(action: {
                //self.presentationMode.projectedValue.wrappedValue.dismiss()
                self.isShowSheet = false
            }){
                Text("Done")
            }
        )
    }
}

Now as you can see, you just need to send a new signal to that isShowSheet binding var - false.

self.isShowSheet = false

Voila!

来源：https://stackoverflow.com/questions/60313431/swiftui-how-to-close-the-sheet-view-while-dismissing-that-view

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ios