Fix ERROR_ALREADY_REQUESTING_PERMISSIONS on iOS after requesting locationAlways (#800)

* trigger callback using notification center

* bump version of permission_handler_apple

* make receiveActivityNotification private

permission_handler_apple/AUTHORS

@@ -5,4 +5,5 @@
 #   Name/Organization <email address>
 
 Baseflow <hello@baseflow.com>
-Maurits van Beusekom <maurits@baseflow.com>
\ No newline at end of file
+Maurits van Beusekom <maurits@baseflow.com>
+Lukas Kurz <me@lukaskurz.com>

permission_handler_apple/CHANGELOG.md

+## 9.0.3
+
+* Ensures a request for `locationAlways` permission returns a result unblocking the permission request and preventing the `ERROR_ALREADY_REQUESTING_PERMISSIONS` error for subsequent permission request.
+
 ## 9.0.2
 
 * Moves Apple implementation into its own package.
\ No newline at end of file

permission_handler_apple/ios/Classes/strategies/LocationPermissionStrategy.m

@@ -7,6 +7,10 @@
 
 #if PERMISSION_LOCATION
 
+@interface LocationPermissionStrategy ()
+- (void) receiveActivityNotification:(NSNotification *)notification;
+@end
+
 @implementation LocationPermissionStrategy {
     CLLocationManager *_locationManager;
     PermissionStatusHandler _permissionStatusHandler;
@@ -53,6 +57,7 @@
         }
     } else if (permission == PermissionGroupLocationAlways) {
         if ([[NSBundle mainBundle] objectForInfoDictionaryKey:@"NSLocationAlwaysUsageDescription"] != nil) {
+            [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveActivityNotification:) name:UIApplicationDidBecomeActiveNotification object:nil];
             [_locationManager requestAlwaysAuthorization];
         } else {
             [[NSException exceptionWithName:NSInternalInconsistencyException reason:@"To use location in iOS8 you need to define NSLocationAlwaysUsageDescription in the app bundle's Info.plist file" userInfo:nil] raise];
@@ -66,6 +71,22 @@
     }
 }
 
+- (void) receiveActivityNotification:(NSNotification *) notification {
+    CLAuthorizationStatus status;
+    if(@available(iOS 14.0, *)){
+        status = _locationManager.authorizationStatus;
+    } else {
+        status = [CLLocationManager authorizationStatus];
+    }
+
+    if ((_requestedPermission == PermissionGroupLocationAlways && status != kCLAuthorizationStatusAuthorizedAlways)) {
+        PermissionStatus permissionStatus = [LocationPermissionStrategy determinePermissionStatus:_requestedPermission authorizationStatus:status];
+
+        _permissionStatusHandler(permissionStatus);
+    }
+    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidBecomeActiveNotification object:nil];    
+}
+
 // {WARNING}
 // This is called when the location manager is first initialized and raises the following situations:
 // 1. When we first request [PermissionGroupLocationWhenInUse] and then [PermissionGroupLocationAlways]

permission_handler_apple/pubspec.yaml

 name: permission_handler_apple
 description: Permission plugin for Flutter. This plugin provides the iOS API to request and check permissions.
-version: 9.0.2
+version: 9.0.3
 homepage: https://github.com/baseflow/flutter-permission-handler
 
 environment: