SheetDismiss.swift

import SwiftUI

struct DetailView : View {
    var body : some View {
        // In order for the dismiss to happen, either NavigationView or VStack has to be commented
        NavigationView {
            VStack {
                InnerView()
            }
            .navigationTitle("Detail")
        }
    }
}

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

    var body: some View {
        VStack {
            Button(action: {
                self.presentationMode.wrappedValue.dismiss()
            }, label: {
                Text("Back")
            })
        }
    }
}

struct ContentView: View {
    @State
    var show: Bool = false

    var body: some View {
        Button(action: {
            self.show = true
        }, label: {
            Text("Show Detail")
        })
        .sheet(isPresented: self.$show) { DetailView() }
    }
}