docs: Update documentation

Author: Dev-hwang

documentation/models_documentation.md

@@ -104,6 +104,16 @@ The level of detail displayed in notifications on the lock screen.
 | `VISIBILITY_SECRET`  | Do not reveal any part of this notification on a secure lockscreen.                                            |
 | `VISIBILITY_PRIVATE` | Show this notification on all lockscreens, but conceal sensitive or private information on secure lockscreens. |
 
+### :chicken: NotificationPermission
+
+enum class: Represents the result of a notification permission request.
+
+| value                | Description                                          |
+|----------------------|------------------------------------------------------|
+| `granted`            | Notification permission has been granted.            |
+| `denied`             | Notification permission has been denied.             |
+| `permanently_denied` | Notification permission has been permanently denied. |
+
 ### :chicken: ServiceRequestResult
 
 sealed class: Represents the result of a service request.
@@ -113,6 +123,13 @@ sealed class: Represents the result of a service request.
 | `ServiceRequestSuccess()`             | The service request was successful. |
 | `ServiceRequestFailure(Object error)` | The service request failed.         |
 
+| error                            | Description                                                                                                    |
+|----------------------------------|----------------------------------------------------------------------------------------------------------------|
+| `ServiceAlreadyStartedException` | The service has already started.                                                                               |
+| `ServiceNotInitializedException` | Not initialized. Please call this function after calling the init function.                                    |
+| `ServiceNotStartedException`     | The service is not started.                                                                                    |
+| `ServiceTimeoutException`        | The service request timed out. (ref: https://developer.android.com/guide/components/services#StartingAService) |
+
 ### :chicken: TaskStarter
 
 The starter that started the task.

documentation/utility_documentation.md

@@ -18,7 +18,16 @@ Launch the app at `route` if it is not running otherwise open it.
 It is also possible to pass a route to this function but the route will only
 be loaded if the app is not already running.
 
+This function requires the `android.permission.SYSTEM_ALERT_WINDOW` permission and 
+requires using the `openSystemAlertWindowSettings()` function to grant the permission.
+
 ```dart
+void requestPermission() async {
+  if (!await FlutterForegroundTask.canDrawOverlays) {
+    await FlutterForegroundTask.openSystemAlertWindowSettings();
+  }
+}
+
 void function() => FlutterForegroundTask.launchApp([route]);
 ```
 
@@ -72,7 +81,7 @@ Future<bool> function() => FlutterForegroundTask.openIgnoreBatteryOptimizationSe
 
 Request to ignore battery optimization.
 
-This function requires `android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS` permission.
+This function requires the `android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS` permission.
 
 > **Warning**
 > It only works when the app is in the foreground.

lib/flutter_foreground_task.dart

@@ -353,6 +353,12 @@ class FlutterForegroundTask {
   static void minimizeApp() => _platform.minimizeApp();
 
   /// Launch the app at [route] if it is not running otherwise open it.
+  ///
+  /// It is also possible to pass a route to this function but the route will only
+  /// be loaded if the app is not already running.
+  ///
+  /// This function requires the "android.permission.SYSTEM\_ALERT\_WINDOW" permission and
+  /// requires using the `openSystemAlertWindowSettings()` function to grant the permission.
   static void launchApp([String? route]) => _platform.launchApp(route);
 
   /// Toggles lockScreen visibility.
@@ -375,7 +381,7 @@ class FlutterForegroundTask {
 
   /// Request to ignore battery optimization.
   ///
-  /// This function requires "android.permission.REQUEST\_IGNORE\_BATTERY\_OPTIMIZATIONS" permission.
+  /// This function requires the "android.permission.REQUEST\_IGNORE\_BATTERY\_OPTIMIZATIONS" permission.
   static Future<bool> requestIgnoreBatteryOptimization() =>
       _platform.requestIgnoreBatteryOptimization();
 

lib/models/notification_permission.dart

@@ -1,6 +1,12 @@
+/// Represents the result of a notification permission request.
 enum NotificationPermission {
+  /// Notification permission has been granted.
   granted,
+
+  /// Notification permission has been denied.
   denied,
+
+  /// Notification permission has been permanently denied.
   permanently_denied;
 
   static NotificationPermission fromIndex(int? index) => NotificationPermission