Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
I'm the author of TriangleDraw, a pixel editor for iPad/iPhone. This is for painting with triangles in a B/W isometric grid. It's possible to export to vector. For this project I use Metal, UIDocumentBrowserViewController and some ruby. It's open source.