WenchaoD/FSCalendar ? reverse-engineered prompt

Build me an iOS calendar component I can drop into an app and customize easily. I want it to show a month grid, let users tap or swipe to select dates, switch between a full month view and a smaller week view with a smooth gesture, and support single or multiple date selection. It should be easy to style with custom cells and work nicely with Interface Builder, Auto Layout, and also in code.

Please make it usable from both Objective C and Swift, and include a simple example app that shows how to set it up and handle delegate and data source callbacks. If it helps, add a Today extension example too, since I’d like to see that working. Keep the calendar flexible and polished, with sensible defaults but lots of room to change the look and behavior. If anything needs current platform guidance, look up the latest docs online.