Drawer — とは、DrawerLayoutとアプリのサイドメニュー

// DrawerLayoutとNavigationViewを使用したアクティビティ
class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding
    private lateinit var drawerLayout: DrawerLayout

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        drawerLayout = binding.drawerLayout
        val navView = binding.navView
        val navController = findNavController(R.id.nav_host_fragment)

        // Navigation ComponentへのDrawerのバインド
        NavigationUI.setupActionBarWithNavController(
            this, navController, drawerLayout
        )
        NavigationUI.setupWithNavController(navView, navController)
    }

    override fun onSupportNavigateUp(): Boolean {
        return NavigationUI.navigateUp(
            findNavController(R.id.nav_host_fragment),
            drawerLayout
        )
    }
}

// XML: activity_main.xml
// <androidx.drawerlayout.widget.DrawerLayout
//   android:id="@+id/drawerLayout"
//   ...>
//   <!-- メインコンテンツ -->
//   <FrameLayout android:id="@+id/nav_host_fragment"
//     android:layout_width="match_parent"
//     android:layout_height="match_parent" />
//   <!-- Navigation Drawer -->
//   <com.google.android.material.navigation.NavigationView
//     android:id="@+id/navView"
//     android:layout_width="wrap_content"
//     android:layout_height="match_parent"
//     android:layout_gravity="start"
//     app:menu="@menu/nav_menu" />
// </androidx.drawerlayout.widget.DrawerLayout>

import SwiftUI

struct DrawerView<Content: View, Menu: View>: View {
    let menuWidth: CGFloat = 280

    @Binding var isOpen: Bool
    @ViewBuilder let content: Content
    @ViewBuilder let menu: Menu

    var body: some View {
        ZStack(alignment: .leading) {
            content
                .offset(x: isOpen ? menuWidth : 0)
                .animation(.easeInOut, value: isOpen)

            if isOpen {
                menu
                    .frame(width: menuWidth)
                    .transition(.move(edge: .leading))

                Color.black.opacity(0.3)
                    .ignoresSafeArea()
                    .onTapGesture { isOpen = false }
            }
        }
    }
}

// 使用法
struct ContentView: View {
    @State private var showDrawer = false

    var body: some View {
        DrawerView(isOpen: $showDrawer) {
            NavigationStack {
                HomeView()
                    .toolbar {
                        ToolbarItem(placement: .navigationBarLeading) {
                            Button(action: { showDrawer.toggle() }) {
                                Image(systemName: "line.horizontal.3")
                            }
                        }
                    }
            }
        } menu: {
            DrawerMenuView()
        }
    }
}

// NavigationViewのカスタムヘッダー
val headerView = binding.navView.inflateHeaderView(R.layout.nav_header)
headerView.findViewById<ImageView>(R.id.iv_avatar)
    .setImageResource(R.drawable.avatar)
headerView.findViewById<TextView>(R.id.tv_name)
    .text = "John Doe"

// メニュー項目の設定
val menuItem = binding.navView.menu.findItem(R.id.nav_notifications)
menuItem.isChecked = true

// バッジの追加
val badge = binding.navView.getOrCreateBadge(R.id.nav_notifications)
badge.number = 15
badge.isVisible = true