I recently ran into an interesting problem working on putting support for the Windows Azure Access Control Service (ACS) into the Windows Azure iOS Toolkit.
It turns out that once you’ve gone through all of the ACS authentication process, a security token is generated. You need this token to authenticate yourself against ACS-bound web sites. However the ACS web site passes the token to you by calling window.external.Notify()
Another mechanism was needed. Here is how I solved it.