您可以使用offset视图修改器来移动侧边栏
下面是一个例子

struct SideBarExample: View {
    @State var showSideBar = false
    var mainView: some View{
        Rectangle()
            .foregroundColor(.blue)
            .overlay(Text("Main View"))
    }
    var sideBar: some View{
        HStack{
            Rectangle()
                .foregroundColor(.green)
                .overlay(Text("side bar"))
                .frame(width:250)
            Spacer()
        }
        

    }
    var body: some View {
        NavigationStack{
            ZStack{
                mainView
                sideBar
                    .offset(CGSize(width: showSideBar ? 0:-250, height: 0))
            }
                .toolbar {
                    ToolbarItem(placement: .navigationBarLeading) {
                        Button {
                            withAnimation {
                                showSideBar.toggle()
                            }
                        } label: {
                            Image(systemName: "sidebar.left")
                        }

                    }
                }
        }
    }
}

的内容如下所示

对于iPhone，你必须构建自己的侧边栏，只需将其覆盖在ZStack中，并使用.transition进行动画制作。

struct ContentView: View {
    
    @State private var showSideBar = false
    
    var mainView: some View{
        Rectangle()
            .foregroundColor(.gray)
            .overlay(Text("Main View"))
    }
    
    var sideBar: some View{
        Rectangle()
            .foregroundColor(.green)
            .overlay(Text("side bar"))
            .frame(width: 200)
    }
    
    var body: some View {
        
        NavigationStack{
            
            ZStack(alignment: .leading) {
                mainView
                
                if showSideBar {
                    sideBar
                        .transition(.move(edge: .leading))
                }
            }
            
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button {
                        withAnimation {
                            showSideBar.toggle()
                        }
                    } label: {
                        Image(systemName: "sidebar.left")
                    }
                    
                }
            }
        }
    }
}