For LP-styled repos, where OF itself is setup as a git submodule and the External Addons also setup as git submodules in the /ExternalAddons folder, creating an ofxApp project can be made simpler;
Note that this only works with this LP-style folder structure!
This document describes how to do this in OF 10.1 style, where OF itself is not added as a subproject to your Xcode project anymore. This was forced by Xcode 10.0 not allowing the same project to be open multiple times, so it meant you could not have two projects open if they both used OpenFrameworks. The same pain applies to ofxApp, so it is not embedded inside your project anymore. If you need that, get an older revision tagged "pre-xcode-10".
Given the number of dependencies, you can alternatively include ofxApp as a Target Dependency instead of manually including all the required addons. The target dependency approach means ofxApp is included as a whole, with all its dependencies defined in an Xcode project file that is part of the addon repository. It also means you don't have to manually manage all the include paths, etc. This approach is the same one that OpenFrameworks uses; in your standard OF app, the Xcode Project includes the OF Xcode project as a target dependency.
The approach here is to do the same with ofxApp:
It should be at the right folder level, either in the "Sketches" folder, or the "Apps" folder at the root of your LP-Style OpenFrameworks repo.
Open your new project, and select your project from the file browser on the left. Navigate to the Build Phases tab. There is a tiny + button on the top left, that allows you to create a new "build phase".
Press the "+" button, and choose New Run Script Phase.
This will create a new entry named "Run Script" at the bottom of the list. Expand it by clicking on the small triangle on the left. Rename it to "build ofxApp", double click on the title to do so. Move this whole new section (via drag & drop) to the third spot on the list.
We place it in 3rd place because the 2nd entry builds OpenFrameworks. ofxApp can only be built after OpenFrameworks is already built.
You then need to copy and paste this command:
xcodebuild -project "$EXT_ADDONS_PATH/ofxApp/ProjectFiles/osx/ofxApp.xcodeproj" -target ofxApp -configuration "${CONFIGURATION}"
into the text input box. You can leave everything else as it is. From now on, whenever you build your project, ofxApp will be built first.
Open your Project.xcconfig and edit it so that it looks like this:
//define the path to OF from within your project
OF_PATH = ../../OpenFrameworks
//and then reference the OF and ofxApp xcconfigs separately
#include "../../OpenFrameworks/libs/openFrameworksCompiled/project/osx/CoreOF.xcconfig"
#include "../../ExternalAddons/ofxApp/ProjectFiles/osx/ofxAppProject.xcconfig"
//ICONS - NEW IN 0072
ICON_NAME_DEBUG = icon-debug.icns
ICON_NAME_RELEASE = icon.icns
ICON_FILE_PATH = $(OF_PATH)/libs/openFrameworksCompiled/project/osx/
Make sure it looks exactly like that, and there's nothing else but that in the Project.xconfig file.
Note that we are including the ofxApp.xcconfig from our project's xcconfig, which effectively adds all the ofxApp dependency includes to our project's. This is what saves us from having to define all include paths, etc. within our project, bc the ofxApp Xcode project already has these defined.
Navigate to the "Build Settings" tab, and look for "Header Search Paths". If its content are rendered in bold type, it means it has been edited, and the edits are overriding the contents of your Project.xcconfig file. We don't want that.
Select it, and press backspace on your keyboard. This will remove these edits, and the field will be rendered in regular type.
Similar as the previous step. Navigate to the "Build Settings" tab, and look for "Other Linker Flags". If its content are rendered in bold type, it means it has been edited, and the edits are overriding the contents of your Project.xcconfig file. We don't want that.
Select it, and press backspace on your keyboard. This will remove these edits, and the field will be rendered in regular type.
Because ofxApp holds globals that are unique per each project, it needs to be compiled together with your project. Because of that, ofxApp itself is not included in the ofxApp.xcodeproj; only its dependencies are.
So, to actually use ofxApp in your project, you need to add it into the project navigator inside your project.
This is as easy as creating a new group named ofxApp within the addons section in the "Project Navigator", and dragging all the ofxApp src files in it.
And more importantly, any new dependencies ofxApp might get in future updates, will be automatically handled when you update ofxApp, because the ofxApp project files are part of the ofxApp repo.
If you need to include more addons, just add them to your project as you normally would.