If you don’t like or don’t have the time for tinkering, we have a binary version built on macOS 11.0.1, using Xcode 12, Qt 5.15.2 and QtWebKit 5.212.0 Alpha4: upplay-1.4.9-webkit.dmg
You can build the software with two approaches:
Use macports or homebrew: npupnp, libupnpp and upplay build just fine, using Qt 5.13 and other tools from the ports (and using the configure scripts).
Use a more native approach, using Qt creator and the .pro files of each project (in the macos directories for npupnp and libupnpp, and the default upplay one). Details follow.
Building without a ports tree
Install Qt with Qt Creator, and XCode (see the Qt docs for this).
Get the webkit install: https://github.com/qtwebkit/qtwebkit/releases Unpack it inside the qt directory (the bin lib etc inside the archive must overlay the existing ones), so move the contents to, e.g. Qt/5.14.2/clang_64/
Extract and build libmicrohttpd 0.9.71. The regular configure/make method bundled with the lib source "just works".
It appears that the rest of the necessary libs (e.g. expat, libcurl) are bundled with Macos.
Extract the source for libnpupnp, libupnppp, and upplay in the same directory where you extracted libmicrohttpd.
Copy libnpupnp-xxx/macos/autoconfig-macos.h to libnpupnp-xxx/autoconfig.h
Copy libnpupnp-xxx/macos/upnpconfig-macos.h to libnpupnp-xxx/inc/upnpconfig.h
Copy libupnpp-xxx/macos/config-macos.h to libupnpp-xxx/libupnpp/config.h
Create directory libnpupnp-xxx/inc/upnp, and copy or link the .h from libnpupnp-xxx/inc into it. Also copy src/inc/netif.h to inc/upnp. This is to mimick what a linux installation would do and allow the build of libupnpp to proceed normally.
Open libnpupnp-xxx/macos/qmk/libnpupnp.pro, libupnpp-xxx/macos/qmk/libupnpp.pro and upplay-xxx/upplay.pro in qtcreator, and build the three projects.
Finally, if needed, generate a .dmg distribution with something like:
./Qt/5.14.2/clang_64/bin/macdeployqt build-upplay-Desktop_Qt_5_14_2_clang_64bit-Release/upplay.app -dmg
The first earlier port was done by a kind Upplay user (who asked to remain anonymous), it was an early version built on Mojave, with a few problems:
Missing entries sometimes in listing Media Server directories.
The multi-tab function is not working: new tabs stay empty, and Upplay later crashes on exit.
The old .dmg is still here until the new one is validated.