How do I make a macOS app out of my Python program?

Question

I've made this question because I had to go through the whole process of creating my own application using Apple's somewhat lacking documentation, and without the use of py2app . I wanted to create the whole application structure so I know exactly what was inside, as well as create an installer for it. The latter of these is still a mystery, so any additional answers with information on making a custom installer would be appreciated. As far as the actual "bundle" structure goes, however, I think I've managed to get the basics down. See the answer below.

Answer 1

Edit: A tutorial has been linked at the end of this answer on using PyInstaller; I don't know how much it helps as I haven't used it yet, but I have yet to figure out how to make a standalone Python application without the use of a tool like this and it may just be what you're looking for if you wish to distribute your application without relying on users knowing how to navigate their Python installations.

A generic application is really just a directory with a .app extension. So, in order to build your application, just make the folder without the extension first. You can rename it later when you're finished putting it all together. Inside this main folder will be a Contents folder, which will hold everything your application needs. Finally, inside Contents , you will place a few things:

1. Info.plist
2. MacOS
3. Resources
4. Frameworks

Here you can find some information on how to write your Info.plist file. Basically, this is where you detail information about your application.

Inside the MacOS you want to place your main executable. I'm not sure that it matters how you write it; at first, I just had a shell script that called python3 ./../Resources/MyApp.py . I didn't think this was very neat though, so eventually I called the GUI from a Python script which became my executable (I used Tkinter to build my application's GUI, and I wrote several modules which I will get to later). So now, my executable was a Python script with a shebang pointing to the Python framework in my application's Frameworks folder, and this script just created an instance of my custom Tk() subclass and ran the mainloop. Both methods worked, though, so unless someone points out a reason to choose one method over the other, feel free to pick. The one thing that I believe is necessary, is that you name your executable the SAME as your application (before adding the .app ). That, I believe, is the only way that MacOS knows to use that file as your application's executable. Here is a source that describes the bundle structure in more detail; it's not a necessary read unless you really want to get into it.

In order to make your executable run smoothly, you want to make sure you know where your Python installation is. If you're like me, the first thing you tried doing on your new Mac was open up Terminal and type in python3 . If this is the case, this prompted you to install the Xcode Command Line tools, which include an installation of Python 3.8.2 (most recent on Xcode 12). Then, this Python installation would be located at /usr/bin/python3 , although it's actually using the Python framework located at

/Applications/Xcode.app/Developer/Library/Frameworks/Python3.framework/Versions/3.8/bin/python3

I believe, but am NOT CERTAIN, that you could simply make a copy of this framework and add it to your Frameworks folder in order to make the app portable. Make a copy of the Python3.framework folder, and add it to your app's Frameworks folder. A quick side note to be wary of; Xcode comes packaged with a lot of useful tools. In my current progress, the tool I am most hurting for is the Fortran compiler (that I believe comes as a part of GCC), which comes with Xcode. I need this to build SciPy with pip install scipy . I'm sure this is not the only package that would require tools that Xcode provides, but SciPy is a pretty popular package and I am currently facing this limitation. I think by copying the Python framework you still lose some of the symlinks that point to Xcode tools, so any additional input on this would be great.

In any case, locate the Python framework that you use to develop your programs, and copy it into the Frameworks folder.

Finally, the Resources folder. Here, place any modules that you wrote for your Python app. You also want to put your application's icon file here. Just make sure you indicate the name of the icon file, with extension, in the Info.plist file. Also, make sure that your executable knows how to access any modules you place in here. You can achieve this with

import os
os.chdir('./../Resources')
import MyModules

Finally, make sure that any dependencies your application requires are located in the Python framework site-packages. These will be located in Frameworks/Python3.framework/Versions/3.XY/lib/python3.xy/site-packages/ . If you call this specific installation of Python from the command line, you can use path/to/application/python3 -m pip install package and it should place the packages in the correct folder.

PS As far as building the installer for this application, there are a few more steps needed before your application is readily downloaded. For instance, I believe you need to use the codesign tool in order to approve your application for MacOS Gatekeeper. This requires having a developer license and manipulating certificates, which I'm not familiar with. You can still distribute the app, but anyone who downloads it will have to bypass the security features manually and it will seem a bit sketchy. If you're ready to build the installer ( .pkg ) file, take a look at the docs for productbuild ; I used it and it works, but I don't yet know how to create custom steps and descriptions in the installer.

Additional resources:

A somewhat more detailed guide to the anatomy of a macOS app

A guide I found, but didn't use, on using codesign to get your app past Gatekeeper

A RealPython tutorial I found on using PyInstaller to build Python-based applications for all platforms