VectorKit is a private framework that handles all graphical rendering for Apple Maps. It parses and renders vector map tiles, stylesheets, and icon packs.

A lot of the code is written in C++, presumably shared with server-side components. In particular, there's some functions to encode files which are likely not used on the client-side, which only needs to decode data retrieved from the server.

• esl: "Easel library", seems to have C++ wrappers for CoreGraphics
• gcl: ?
• gdc: GeoDisplayCore
• ggl: GeoGL (was OpenGL renderer, now has the Metal implementation)
• grl: GeoResourceLib
• gss: GeoCSS (style sheets)
• md: ?
• md::ita: ?
• md::ls: ?
• md::mun: Munin (Look Around)