@shreyas tried doing that its still nil, in fact also tried resetting the keychain using Blockstack.shared.promptClearDeviceKeychain(), it gives the invalid address error, I have attached a screenshot.
I was trying to reset the keychain because that problem where just the using the iOS sdk was overwriting the profile of the user (discussed here) was coming back.
That reset did work actually instead of giving that error.
However, then I ran into another problem when I created a new blockstack ID to test using the desktop browser, when I restored into the iOS simulator, the sign in work but it is giving Blockstack.shared.loadUserData()?.username and Blockstack.shared.loadUserData()?.claim as nil.
So, these are basically 3 different problems. 
Let me know if you need any more information or if you are not able to reproduce them.
I was basically hoping to use newly formed test IDs to submit as part of my submission to the app store. However, seems like I will have to find a work around.