Custom back button for NavigationView’s navigation bar in SwiftUI

TL;DR

Use this to transition to your view:

NavigationLink(destination: SampleDetails()) {}

Add this to the view itself:

@Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>

Then, in a button action or something, dismiss the view:

presentationMode.wrappedValue.dismiss()

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Full code

From a parent, navigate using NavigationLink

 NavigationLink(destination: SampleDetails()) {}

In DetailsView hide navigationBarBackButton and set custom back button to leading navigationBarItem,

struct SampleDetails: View {
    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>

    var btnBack : some View { Button(action: {
        self.presentationMode.wrappedValue.dismiss()
        }) {
            HStack {
            Image("ic_back") // set image here
                .aspectRatio(contentMode: .fit)
                .foregroundColor(.white)
                Text("Go back")
            }
        }
    }
    
    var body: some View {
            List {
                Text("sample code")
        }
        .navigationBarBackButtonHidden(true)
        .navigationBarItems(leading: btnBack)
    }
}