OpenEmu uses a modular architecture, allowing for game-engine plugins, allowing OpenEmu to support a host of different emulation engines and back ends while retaining the familiar macOS and iOS native front end.
One third-party library example is Sparkle, which is used for auto-updating. The project leverages modern macOS technologies, such as Cocoa, Core Animation with Quartz Composer, and other third-party libraries. OpenEmu for macOS and iOS is an open source Emulator project whose purpose is to bring macOS game emulation into the realm of first class citizenship.
OpenEmu – Multiple Video Game System for macOS (OS X) and iOS Version