Fixing preventDefault behavior

In order to get preventDefault() and display() to work the bridge layer listener needs to call preventDefault() so that the notification does not display before the flutter listeners have had a chance to call preventDefault(). Once all of the flutter listeners have responded to the event, if none of them have called preventDefault then the bridge layer will call display().

Author: emawby

android/src/main/java/com/onesignal/flutter/OneSignalNotifications.java

@@ -38,6 +38,8 @@
 
 public class OneSignalNotifications extends FlutterRegistrarResponder implements MethodCallHandler, INotificationClickListener, INotificationLifecycleListener, IPermissionObserver {
     private final HashMap<String, INotificationWillDisplayEvent> notificationOnWillDisplayEventCache = new HashMap<>();
+    private final HashMap<String, INotificationWillDisplayEvent> preventedDefaultCache = new HashMap<>();
+
 
     static void registerWith(BinaryMessenger messenger) {
         OneSignalNotifications controller = new OneSignalNotifications();
@@ -64,14 +66,17 @@ else if (call.method.contentEquals("OneSignal#preventDefault"))
         this.preventDefault(call, result);
     else if (call.method.contentEquals("OneSignal#lifecycleInit"))
         this.lifecycleInit();
+    else if (call.method.contentEquals("OneSignal#proceedWithWillDisplay"))
+        this.proceedWithWillDisplay(call, result);
     else
         replyNotImplemented(result);
     }
 
     private void requestPermission(MethodCall call, Result result) {
         boolean fallback = (boolean) call.argument("fallbackToSettings");
-        OneSignal.getNotifications().requestPermission(fallback, Continue.none());
-        replySuccess(result, null);
+        OneSignal.getNotifications().requestPermission(fallback, Continue.with(permissionResult -> {
+            replySuccess(result, permissionResult.getData());
+        }));
     }
 
     private void removeNotification(MethodCall call, Result result) {
@@ -93,6 +98,24 @@ private void clearAll(MethodCall call, Result result) {
         replySuccess(result, null);
     }
 
+    /// Our bridge layer needs to preventDefault() so that the Flutter listener has time to preventDefault() before the notification is displayed
+    /// This function is called after all of the flutter listeners have responded to the willDisplay event. 
+    /// If any of them have called preventDefault() we will not call display(). Otherwise we will display.
+    private void proceedWithWillDisplay(MethodCall call, Result result) {
+        String notificationId = call.argument("notificationId");
+        INotificationWillDisplayEvent event = notificationOnWillDisplayEventCache.get(notificationId);
+        if (event == null) {
+            Logging.error("Could not find onWillDisplayNotification event for notification with id: " + notificationId, null);
+            return;
+        }
+        if (this.preventedDefaultCache.containsKey(notificationId)) {
+            replySuccess(result, null);
+            return;
+        }
+        event.getNotification().display();
+        replySuccess(result, null);
+    }
+
     private void displayNotification(MethodCall call, Result result) {
         String notificationId = call.argument("notificationId");
         INotificationWillDisplayEvent event = notificationOnWillDisplayEventCache.get(notificationId);
@@ -112,6 +135,7 @@ private void preventDefault(MethodCall call, Result result) {
             return;
         }
         event.preventDefault();
+        this.preventedDefaultCache.put(notificationId, event);
         replySuccess(result, null);
     }
 
@@ -141,6 +165,8 @@ private JSONObject getJsonFromMap(Map<String, Object> map) throws JSONException
     public void onWillDisplay(INotificationWillDisplayEvent event) {
         INotification notification = event.getNotification();
         notificationOnWillDisplayEventCache.put(notification.getNotificationId(), event);
+        /// Our bridge layer needs to preventDefault() so that the Flutter listener has time to preventDefault() before the notification is displayed
+        event.preventDefault();
         try {
             invokeMethodOnUiThread("OneSignal#onWillDisplayNotification", OneSignalSerializer.convertNotificationWillDisplayEventToMap(event));
         } catch (JSONException e) {

ios/Classes/OSFlutterNotifications.h

@@ -35,6 +35,6 @@
 @property (strong, nonatomic) FlutterMethodChannel *channel;
 + (instancetype)sharedInstance;
 @property (strong, nonatomic) NSMutableDictionary* onWillDisplayEventCache;
-
+@property (strong, nonatomic) NSMutableDictionary* preventedDefaultCache;
 
 @end

ios/Classes/OSFlutterNotifications.m

@@ -38,6 +38,7 @@ + (instancetype)sharedInstance {
     dispatch_once(&onceToken, ^{
         sharedInstance = [OSFlutterNotifications new];
         sharedInstance.onWillDisplayEventCache = [NSMutableDictionary new];
+        sharedInstance.preventedDefaultCache = [NSMutableDictionary new];
     });
     return sharedInstance;
 }
@@ -70,6 +71,8 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
         [self preventDefault:call withResult:result];
      else if ([@"OneSignal#lifecycleInit" isEqualToString:call.method])
         [self lifecycleInit:call withResult:result];
+    else if ([@"OneSignal#proceedWithWillDisplay" isEqualToString:call.method])
+        [self proceedWithWillDisplay:call withResult:result];
     else
         result(FlutterMethodNotImplemented);
 }
@@ -113,9 +116,28 @@ - (void)onNotificationPermissionDidChange:(BOOL)permission {
 
 - (void)onWillDisplayNotification:(OSNotificationWillDisplayEvent *)event {
     self.onWillDisplayEventCache[event.notification.notificationId] = event;
+    /// Our bridge layer needs to preventDefault so that the Flutter listener has time to preventDefault before the notification is displayed
+    [event preventDefault];
     [self.channel invokeMethod:@"OneSignal#onWillDisplayNotification" arguments:event.toJson];
 }
 
+    /// Our bridge layer needs to preventDefault so that the Flutter listener has time to preventDefault before the notification is displayed
+    /// This function is called after all of the flutter listeners have responded to the willDisplay event. 
+    /// If any of them have called preventDefault we will not call display(). Otherwise we will display.
+- (void)proceedWithWillDisplay:(FlutterMethodCall *)call withResult:(FlutterResult)result {
+    NSString *notificationId = call.arguments[@"notificationId"];
+    OSNotificationWillDisplayEvent *event = self.onWillDisplayEventCache[notificationId];
+    if (!event) {
+        [OneSignalLog onesignalLog:ONE_S_LL_ERROR message:[NSString stringWithFormat:@"OneSignal (objc): could not find notification will display event for notification with id: %@", notificationId]];
+        return;
+    }
+    if (self.preventedDefaultCache[notificationId]) {
+        return;
+    }
+    [event.notification display];
+    result(nil);
+}
+
 - (void)preventDefault:(FlutterMethodCall *)call withResult:(FlutterResult)result {
     NSString *notificationId = call.arguments[@"notificationId"];
     OSNotificationWillDisplayEvent *event = self.onWillDisplayEventCache[notificationId];
@@ -125,6 +147,8 @@ - (void)preventDefault:(FlutterMethodCall *)call withResult:(FlutterResult)resul
         return;
     }
     [event preventDefault];
+    self.preventedDefaultCache[event.notification.notificationId] = event;
+    result(nil);
 }
 
 - (void)displayNotification:(FlutterMethodCall *)call withResult:(FlutterResult)result {
@@ -136,6 +160,7 @@ - (void)displayNotification:(FlutterMethodCall *)call withResult:(FlutterResult)
         return;
     }
     [event.notification display];
+    result(nil);
 }
 
 #pragma mark Notification Click

lib/src/notifications.dart

@@ -133,6 +133,10 @@ class OneSignalNotifications {
         listener.onWillDisplayNotification(OSNotificationWillDisplayEvent(
             call.arguments.cast<String, dynamic>()));
       }
+      var event = OSNotificationWillDisplayEvent(
+          call.arguments.cast<String, dynamic>());
+      _channel.invokeMethod("OneSignal#proceedWithWillDisplay",
+          {'notificationId': event.notification.notificationId});
     } else if (call.method == 'OneSignal#onNotificationPermissionDidChange') {
       this.onNotificationPermissionDidChange(call.arguments["permission"]);
     }