Building a 2FA App That Notifies You of Cool Number Sequences

Inspired by the nostalgic "GET" meme from early image boards, the author built an app that leverages the patterns in 2FA codes. The app generates 6-digit 2FA codes and sends push notifications when interesting number sequences (like repeating digits or consecutive numbers) appear. The article details the development process, from implementing the TOTP algorithm and scheduling notifications to UI design and performance optimization using Combine and Metal shaders. Challenges included handling background processes and efficient code generation. The final app is released, with future plans for performance improvements and additional features.