#695 [feature] Double back press to exit app on MainScreen

Author: yuni-ju

presentation/src/main/java/daily/dayo/presentation/activity/MainActivity.kt

@@ -45,7 +45,8 @@ class MainActivity : AppCompatActivity() {
                 MainScreen(
                     onAdRequest = { onRewardSuccess ->
                         showAdIfAvailable(onRewardSuccess)
-                    }
+                    },
+                    onExit = { finish() }
                 )
             }
         }

presentation/src/main/java/daily/dayo/presentation/screen/main/MainNavigator.kt

@@ -212,8 +212,13 @@ class MainNavigator(
         navController.navigatePostLikeUsers(postId = postId)
     }
 
-    fun navigateUp() {
-        navController.navigateUp()
+    fun navigateUp(): Boolean {
+        return if (navController.previousBackStackEntry != null) {
+            navController.navigateUp()
+            true
+        } else {
+            false
+        }
     }
 
     @Composable

presentation/src/main/java/daily/dayo/presentation/screen/main/MainScreen.kt

@@ -1,5 +1,7 @@
 package daily.dayo.presentation.screen.main
 
+import android.widget.Toast
+import androidx.activity.compose.BackHandler
 import androidx.annotation.DrawableRes
 import androidx.annotation.StringRes
 import androidx.compose.animation.ExperimentalSharedTransitionApi
@@ -30,13 +32,15 @@ import androidx.compose.material3.SnackbarHostState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableLongStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.res.vectorResource
 import androidx.compose.ui.tooling.preview.Preview
@@ -78,6 +82,7 @@ import kotlinx.coroutines.launch
 @Composable
 internal fun MainScreen(
     onAdRequest: (onRewardSuccess: () -> Unit) -> Unit,
+    onExit: () -> Unit,
     navigator: MainNavigator = rememberMainNavigator(),
     profileViewModel: ProfileViewModel = hiltViewModel()
 ) {
@@ -92,6 +97,22 @@ internal fun MainScreen(
         derivedStateOf { if (bottomSheetState.bottomSheetState.currentValue == SheetValue.Expanded) 0.6f else 0f }
     }
     val animatedDimAlpha by animateFloatAsState(targetValue = bottomSheetDimAlpha)
+    val context = LocalContext.current
+    var lastBackPressedTime by remember { mutableLongStateOf(0L) }
+    val toast = remember { Toast.makeText(context, context.getString(R.string.main_finish_toast), Toast.LENGTH_SHORT) }
+
+    BackHandler {
+        if (!navigator.navigateUp()) { // 뒤로갈 화면 없는 경우
+            val currentTime = System.currentTimeMillis()
+            if (currentTime - lastBackPressedTime < 2000) {
+                toast?.cancel()
+                onExit() // 앱 종료
+            } else {
+                lastBackPressedTime = currentTime
+                toast?.show()
+            }
+        }
+    }
 
     SharedTransitionLayout {
         BottomSheetScaffold(

presentation/src/main/res/values/strings.xml

@@ -55,6 +55,9 @@
     <string name="permission_fail_second">DENIED</string>
     <string name="permission_fail_final">EXPLAINED</string>
 
+    <!-- Main -->
+    <string name="main_finish_toast">한 번 더 누르면 앱이 종료됩니다.</string>
+
     <!-- OnBoarding -->
     <string name="onboarding_first_message">인기가 많은 다꾸들을 구경할 수 있어요</string>
     <string name="onboarding_second_message">내 취향의 다꾸러들을 팔로우하고 모아볼 수 있어요</string>