SwiftUI: Sizing a popover to fit

问题

I've got a little popover sample in which a button triggers a popover. The popover only contains a little bit of UI, two buttons in this case, but it still takes up a lot of space instead of wrapping neatly around the content like I'm used to from UIKit. How do I make the popover fit to the size of the content?

Screenshot from the iPad simulator and code below:

struct ContentView: View {

    @State private var showingPopupA = false

    var body: some View {
        HStack {
            Button(action: {
                self.showingPopupA.toggle()
            }, label: {
                Text("Button")
            }).popover(isPresented: self.$showingPopupA) {
                VStack {
                    Button(action: {
                        // Do something
                        self.showingPopupA = false
                    }) {
                        Text("Option A")
                    }
                    Button(action: {
                        // Do something
                        self.showingPopupA = false
                    }) {
                        Text("Option B")
                    }
                }.background(Color.red)
            }
        }
    }
}

Screenshot from macOS:

回答1:

On macOS the code below will look like this:

struct PopoverExample: View {

    @State private var showingPopupA:Bool = false 
    var body: some View {
        HStack {
            Button(action: {
                self.showingPopupA.toggle()
            }, label: {
                Text("Button")
            }).popover(isPresented: self.$showingPopupA) {
                VStack {
                    Button(action: {
                        // Do something
                        self.showingPopupA = false
                    }) {
                        Text("Option A")
                    }
                    Button(action: {
                        // Do something
                        self.showingPopupA = false
                    }) {
                        Text("Option B")
                    }
                }.background(Color.red)
            }
        }
        .frame( maxWidth: .infinity, maxHeight: .infinity)
    }
}

Project link

来源：https://stackoverflow.com/questions/58179317/swiftui-sizing-a-popover-to-fit