Color Before the Lines: reverse coloring for iPad and iPhone. My own product, from concept to the App Store. The watercolor is already on the page; you add the lines, with a finger or Apple Pencil. I designed and built it in Swift: the calm, no-rules flow, the onboarding, the collection and the drawing canvas. Key product decisions: I prototyped three ways to generate backgrounds in code, then shipped hand-painted watercolors because they looked clearly better. I kept the tools to three, so nothing gets in the way of drawing. And it's one universal app, where the iPhone layout is designed for a fingertip, not shrunk from the iPad. Drawings stay on the device and analytics are anonymous.