See also this Sketch Layer Sample on GitHub.
And although this sample is for the OS X SDK, the principles are much the same. That page also includes a link to this download page for the Samples app (look in the app under "Building Maps --> Sketch Layer").
Hope that gives you some answers.
I just stumbled on your message from a year ago. Did you ever come up with a solution? Your redlining/annotation problem is the same problem I'm attempting to solve today. I'm close. I would love to compare notes with you if you are interested.