What is riddle-ipad?

Riddle iPad turns your tablet into a version of Tom Riddle's diary from the Harry Potter stories. You write on the screen with an Apple Pencil, the page appears to soak up your ink, and after you rest the pen for a moment an answer writes itself back in flowing handwriting, one stroke at a time, before fading away. There is no chat window, no buttons, and no keyboard involved. The whole experience is just ink appearing on paper. This project is an iPad version of an existing app called Riddle, which was originally built for the reMarkable tablet. The handwriting generation system and the diary personality both come from that original project, and this repository focuses on porting the idea to iPadOS with Apple Pencil support. Under the hood, your pencil strokes are captured with Apple's PencilKit framework. When you pause writing for a couple of seconds, the page is turned into an image and sent to a vision capable AI model that understands both text and pictures. The model writes its reply, and that reply is converted into realistic pen strokes using a font rendering and thinning process, then animated onto the screen so it looks like it is being handwritten in real time, at a natural pace. The system works with any font, so it can reply in cursive style English or in a handwritten Chinese script, always matching whatever language you wrote in. To run this project yourself you need a Mac with Xcode, a physical iPad running iPadOS 17 or later with Apple Pencil support, and an API key for any AI service that offers a vision capable chat model compatible with the OpenAI API format. The default setup points to a provider called Moonshot, but you can swap in a different one by editing a configuration file. Setup involves installing a tool called XcodeGen, generating the Xcode project, adding your API key to a config file, then building and running the app directly on your iPad. The project is released under the MIT license, and credits the original algorithm, diary concept, and fonts used to their respective creators.