Apps written for macOS are usually written with Apple's Frameworks. The frameworks that almost every app will use are:

• AppKit - for creating and managing UI elements
• Foundation - for common non-UI objects and operations

There are other common frameworks that are used in many, but not all apps:

• CoreData - for data storage
• Dispatch - for management of multiple threads
• CoreGraphics - for drawing a graphics related tasks
• CoreAnimation - for animation of UI elements