The UXReader PDF Framework for macOS is a fully open-source macOS PDF reader/viewer framework based on the open-source PDFium library.
The code is written in Objective-C++ (works with Swift or plain Objective-C) and does not require storyboards or NIBs (all UI elements are generated in code with graphics resources bundled in the framework).
After cloning or downloading the sources, you will need to download the PDFium lib*.a files ZIP and extract it over the UXReader/UXReader/PDFium directory before building in Xcode.
Email: joklamcak(at)gmail(dot)com
Twitter: @joklamcak
This code has been made available under the MIT License.