Good example which shows a pop-up menu after clicking on navigation button.
Original project is here https://github.com/liufengting/FTPopOverMenu
If you want to customize pop over menu then goto FTConstants.swift file and do custom changes.
Example:
internal static let DefaultMenuIconSize = CGFloat(24) // you can change icon size here
internal static let DefaultMenuWidth = CGFloat(150) // default 120