With Adobe announcing a coming gouging and screwing, just noticed that Adobe Ideas, a universal sketching VECTOR app is now free, from $9.99. Went on sale a few days ago so no idea when it's going back up.
Thanks for the heads up. Ideas is a good companion to the Procreate app which is far and away the best sketch, paint, create app on the App Store. It's $5.99 (I think) but you will not regret it. They have a very talented community of users that you can check out if you're not convinced. Right now, they're in beta for a major new release.
I'm not associated with them except as an enthusiastic user. These guys have done an amazing job. And they answered my emails, like right away. Answer my emails and I'll follow you anywhere