I have built a Web Map in Portal for ArcGIS. It uses Services exposed by a Federated ArcGIS for Server 10.2 server. The security applied to Portal is the Portal Built-in Security (Token-Based).
The WebMap works just fine in the Portal for ArcGIS.com Viewer, works perfectly in both the Collector and ArcGIS app for Android (tested it in smartphones and tablets) but it does not work in the iOS Collector and ArcGIS app versions ...
I have tested with an iPhone 4 (iOS 6) and with an iPad 2 (iOS 7). The map opens the basemap and can't even zoom in to the extent defined in the Portal Web Map.
The current released versions of the ArcGIS for iOS app and the iOS Collector app do not fully support Portal 10.2. The upcoming update to the Collector app will include Portal 10.2 support. As a work around if you take your portal service item that is not displaying in the map and if you share it with your entire portal the layer will load in the map. The ArcGIS for iOS app will also have 10.2 portal support in its next update as well.
From our tests only when sharing the AGS services with Everyone is that the applications are able of loading the services appropriately. The workaround you are proposing is only viable if our data would be made of Map Services which is not the case. Most of our WebMap uses Feature Server services that we don't want them to be publicly exposed for security reasons.
Considering the above, can you tell me when it is planned for the new 10.2 releases to come out?