only register with the native listener once a dart listener has been added

Author: emawby

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

@@ -68,6 +68,8 @@ else if (call.method.contentEquals("OneSignal#lifecycleInit"))
         this.lifecycleInit();
     else if (call.method.contentEquals("OneSignal#proceedWithWillDisplay"))
         this.proceedWithWillDisplay(call, result);
+    else if (call.method.contentEquals("OneSignal#addNativeClickListener"))
+        this.registerClickListener();
     else
         replyNotImplemented(result);
     }
@@ -184,7 +186,10 @@ public void onNotificationPermissionChange(boolean permission)  {
 
     private void lifecycleInit() {
         OneSignal.getNotifications().addForegroundLifecycleListener(this);
-        OneSignal.getNotifications().addClickListener(this);
         OneSignal.getNotifications().addPermissionObserver(this);
     }
+
+    private void registerClickListener() {
+        OneSignal.getNotifications().addClickListener(this);
+    }
 } 

ios/Classes/OSFlutterNotifications.m

@@ -73,6 +73,8 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
         [self lifecycleInit:call withResult:result];
     else if ([@"OneSignal#proceedWithWillDisplay" isEqualToString:call.method])
         [self proceedWithWillDisplay:call withResult:result];
+    else if ([@"OneSignal#addNativeClickListener" isEqualToString:call.method])
+        [self registerClickListener:call withResult:result];
     else
         result(FlutterMethodNotImplemented);
 }
@@ -103,11 +105,15 @@ - (void)registerForProvisionalAuthorization:(FlutterMethodCall *)call withResult
 
 - (void)lifecycleInit:(FlutterMethodCall *)call withResult:(FlutterResult)result {
     [OneSignal.Notifications addForegroundLifecycleListener:self];
-    [OneSignal.Notifications addClickListener:self];
     [OneSignal.Notifications addPermissionObserver:self];
     result(nil);
 }
 
+- (void)registerClickListener:(FlutterMethodCall *)call withResult:(FlutterResult)result {
+    [OneSignal.Notifications addClickListener:self];
+    result(nil);
+}
+
 - (void)onNotificationPermissionDidChange:(BOOL)permission {
     [self.channel invokeMethod:@"OneSignal#onNotificationPermissionDidChange" arguments:@{@"permission" : @(permission)}];
 }

lib/src/notifications.dart

@@ -31,6 +31,8 @@ class OneSignalNotifications {
 
   bool _permission = false;
 
+  bool _clickHandlerRegistered = false;
+
   /// Whether this app has push notification permission.
   bool get permission {
     return _permission;
@@ -177,6 +179,10 @@ class OneSignalNotifications {
   /// The notification click listener is called whenever the user opens a
   /// OneSignal push notification, or taps an action button on a notification.
   void addClickListener(OnNotificationClickListener listener) {
+    if (!_clickHandlerRegistered) {
+      _clickHandlerRegistered = true;
+      _channel.invokeMethod("OneSignal#addNativeClickListener");
+    }
     _clickListeners.add(listener);
   }