Jetpack Compose で Runtime Permission をリクエストする

onStart() でパーミッションがあるかどうかチェックして、無い場合はパーミッションをリクエストする処理です。

rememberLauncherForActivityResult()　を使います。

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1. enum class PermissionState {  
2.     Checking,  
3.     Granted,  
4.     Denied,  
5. }  
6.   
7. @Composable  
8. private fun NeedPermissionScreen() {  
9.     var state by remember { mutableStateOf(PermissionState.Checking) }  
10.   
11.     val launcher = rememberLauncherForActivityResult(ActivityResultContracts.RequestPermission()) {  
12.         state = if (it) PermissionState.Granted else PermissionState.Denied  
13.     }  
14.   
15.     val permission = Manifest.permission.CAMERA  
16.   
17.     val context = LocalContext.current  
18.     val lifecycleObserver = remember {  
19.         LifecycleEventObserver { _, event ->  
20.             if (event == Lifecycle.Event.ON_START) {  
21.                 val result = context.checkSelfPermission(permission)  
22.                 if (result != PackageManager.PERMISSION_GRANTED) {  
23.                     state = PermissionState.Checking  
24.                     launcher.launch(permission)  
25.                 } else {  
26.                     state = PermissionState.Granted  
27.                 }  
28.             }  
29.         }  
30.     }  
31.     val lifecycle = LocalLifecycleOwner.current.lifecycle  
32.     DisposableEffect(lifecycle, lifecycleObserver) {  
33.         lifecycle.addObserver(lifecycleObserver)  
34.         onDispose {  
35.             lifecycle.removeObserver(lifecycleObserver)  
36.         }  
37.     }  
38.   
39.     when (state) {  
40.         PermissionState.Checking -> {  
41.         }  
42.         PermissionState.Granted -> {  
43.             // TODO パーミッションが必要な機能を使う画面  
44.         }  
45.         PermissionState.Denied -> {  
46.             // TODO 拒否された時の画面  
47.         }  
48.     }  
49. }  

enum class PermissionState { Checking, Granted, Denied, } @Composable private fun NeedPermissionScreen() { var state by remember { mutableStateOf(PermissionState.Checking) } val launcher = rememberLauncherForActivityResult(ActivityResultContracts.RequestPermission()) { state = if (it) PermissionState.Granted else PermissionState.Denied } val permission = Manifest.permission.CAMERA val context = LocalContext.current val lifecycleObserver = remember { LifecycleEventObserver { _, event -> if (event == Lifecycle.Event.ON_START) { val result = context.checkSelfPermission(permission) if (result != PackageManager.PERMISSION_GRANTED) { state = PermissionState.Checking launcher.launch(permission) } else { state = PermissionState.Granted } } } } val lifecycle = LocalLifecycleOwner.current.lifecycle DisposableEffect(lifecycle, lifecycleObserver) { lifecycle.addObserver(lifecycleObserver) onDispose { lifecycle.removeObserver(lifecycleObserver) } } when (state) { PermissionState.Checking -> { } PermissionState.Granted -> { // TODO パーミッションが必要な機能を使う画面 } PermissionState.Denied -> { // TODO 拒否された時の画面 } } }

追記:
Accompanist に最近 Permission のやつが追加されました （現状 Permission 関係のすべての機能は experimental）

https://google.github.io/accompanist/permissions/