Fixed parsing for 'notification_ids' after changes to iOS SDK

* Handle the case for if the 'notification_ids' in OSOutcomeEvent is a List as a string or as a List
* Removed not needed @implementation inside of 'OSFlutterCategories'

Author: mikechoch

ios/Classes/OSFlutterCategories.h

@@ -47,11 +47,6 @@
 - (NSDictionary *)toJson;
 @end
 
-// TODO: Will reference the OSOutcomeEvent in OneSignal.h
-//@interface OSOutcomeEvent (Flutter)
-//- (NSDictionary *)toJson;
-//@end
-
 @interface NSError (Flutter)
 - (FlutterError *)flutterError;
 @end

ios/Classes/OSFlutterCategories.m

@@ -112,21 +112,6 @@ - (NSDictionary *)toJson {
 }
 @end
 
-// TODO: Will reference the OSOutcomeEvent in OneSignal.h
-//@implementation OSOutcomeEvent (Flutter)
-//- (NSDictionary *)toJson {
-//    NSMutableDictionary *json = [NSMutableDictionary new];
-//
-//    json[@"session"] = self.session;
-//    json[@"notification_ids"] = self.notificationIds;
-//    json[@"name"] = self.name;
-//    json[@"timestamp"] = self.timestamp;
-//    json[@"weight"] = self.weight;
-//
-//    return json;
-//}
-//@end
-
 @implementation NSError (Flutter)
 - (FlutterError *)flutterError {
     return [FlutterError errorWithCode:[NSString stringWithFormat:@"%i", (int)self.code] message:self.localizedDescription details:nil];

lib/src/outcome_event.dart

@@ -46,9 +46,16 @@ class OSOutcomeEvent extends JSONStringRepresentable {
                      OSSession.DISABLED;
 
       // Make sure notification_ids exists
-      this.notificationIds = outcome.containsKey("notification_ids") && outcome["notification_ids"] != null ?
-                             new List<String>.from(json.decode(outcome["notification_ids"])) :
-                             [];
+      if (outcome.containsKey("notification_ids") && outcome["notification_ids"] != null) {
+        if (outcome["notification_ids"] is List) {
+          // Handle if type comes in as a List
+          this.notificationIds = (outcome["notification_ids"] as List).map<String>((s) => s).toList();
+        }
+        else if (outcome["notification_ids"] is String) {
+          // Handle if type comes in as a String
+          this.notificationIds = new List<String>.from(json.decode(outcome["notification_ids"]));
+        }
+      }
 
       // Make sure name exists
       this.name = outcome.containsKey("id") && outcome["id"] != null ?