fix(badges): Use hasBadge flag to indicate badge count is set

* This fixes a bug when a notification had "SetTo" = 0; our check for the existence of notification.badge could not differentiate null vs 0, and we detected 0 as lack of existence.

* Using a flag let's us differentiate between null vs 0 badge count. The payload from APNS will be already be an NSNumber: https://developer.apple.com/documentation/usernotifications/unnotificationcontent/badge?language=objc and we will set the flag if there is a badge

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalCore/Source/OSNotification.h

@@ -59,6 +59,9 @@
 @property(readonly, nullable)NSString* category;
 
 /* The badge assigned to the application icon */
+/// Indicates if badge count is set on this notification; this flag is needed as the `badge` property is an
+/// integer primitive and cannot be used to differentiate between null badge vs badge count of 0.
+@property(readonly)BOOL hasBadge;
 @property(readonly)NSInteger badge;
 @property(readonly)NSInteger badgeIncrement;
 

iOS_SDK/OneSignalSDK/OneSignalCore/Source/OSNotification.m

@@ -124,6 +124,7 @@ - (void)parseCommonOneSignalFields:(NSDictionary*)payload {
 
 - (void)parseApnsFields {
     [self parseAlertField:_rawPayload[@"aps"][@"alert"]];
+    _hasBadge = _rawPayload[@"aps"][@"badge"] ? true : false;
     _badge = [_rawPayload[@"aps"][@"badge"] intValue];
     _sound = _rawPayload[@"aps"][@"sound"];
 }
@@ -257,7 +258,9 @@ - (NSDictionary *)jsonRepresentation {
     if (self.templateId)
         [obj setObject:self.templateId forKeyedSubscript: @"templateId"];
 
-    if (self.badge)
+    [obj setObject:@(self.hasBadge) forKeyedSubscript: @"hasBadge"];
+
+    if (self.hasBadge)
         [obj setObject:@(self.badge) forKeyedSubscript: @"badge"];
 
     if (self.badgeIncrement)

iOS_SDK/OneSignalSDK/OneSignalExtension/OneSignalExtensionBadgeHandler.m

@@ -34,7 +34,7 @@ + (void)handleBadgeCountWithNotificationRequest:(UNNotificationRequest *)request
     //if the user is setting the badge directly instead of incrementing/decrementing,
     //make sure the OneSignal cached value is updated to this value
     if (!notification.badgeIncrement) {
-        if (notification.badge)
+        if (notification.hasBadge)
             [OneSignalExtensionBadgeHandler updateCachedBadgeValue:notification.badge];
 
         return;

iOS_SDK/OneSignalSDK/OneSignalNotifications/OSNotificationsManager.m

@@ -985,7 +985,7 @@ + (UNNotificationRequest*)prepareUNNotificationRequest:(OSNotification*)notifica
     else
         content.sound = UNNotificationSound.defaultSound;
 
-    if (notification.badge != 0)
+    if (notification.hasBadge)
         content.badge = [NSNumber numberWithInteger:notification.badge];
 
     // Check if media attached