How I build CR2toJPG converter Mac App

I used py2app module to convert my existing python app which uses Pillow for image conversion and Tkinter to make the UI for Mac App
I build the setup.py file where main.py is the Python file which has everthing.

from setuptools import setup

APP = ['main.py']
DATA_FILES = []
OPTIONS = {
  'argv_emulation': False,
  'packages': ['tkinter','PIL'],
}

setup(
    app=APP,
    data_files=DATA_FILES,
    options={'py2app': OPTIONS},
    setup_requires=['py2app'],
)

Keep note to add all the required packages on OPTIONS . I had some try/error where once I build an APP i had debug

I had to go

/dist/main.app/Contents/MacOS

Inside this we can find the app just run that it will give us the error if it's not running

Now time for converting it to dmg file

To distribute the CR2toJPG converter as a user-friendly Mac application, converting the .app bundle to a disk image (.dmg) was the next logical step. This format is widely recognized in the macOS ecosystem for distributing software, offering a seamless installation experience for users. Below is a detailed guide on how the .app was converted to a .dmg file and the rationale behind it.

Why Convert to DMG?

A .dmg file serves multiple purposes in macOS software distribution:

Security: It offers a layer of security, ensuring that the app hasn't been tampered with since it was packaged.
Integrity: Disk images are less prone to corruption during download.
User Experience: Provides a familiar installation process for Mac users, often with drag-and-drop simplicity into the Applications folder.
Customization: Allows for branding opportunities, such as custom background images and license agreements.

Steps to Convert `.app` to `.dmg`

Preparing the Application

Ensure the CR2toJPG converter .app is finalized, tested, and located in your project's dist directory after packaging with Py2app.

Creating the Disk Image

Open Terminal on your Mac and navigate to the directory containing the .app.
Execute the hdiutil Command: Use hdiutil, a built-in macOS utility, to create the .dmg:
```
 hdiutil create -volname "CR2toJPG Converter" -srcfolder ./dist/main.app -ov -format UDZO "CR2toJPGConverter.dmg"
```
Breakdown of the command:
- -volname "CR2toJPG Converter": Sets the name of the mounted volume.
- -srcfolder ./dist/CR2toJPGConverter.app: Specifies the path to the .app.
- -ov: Overwrites an existing .dmg file if it exists.
- -format UDZO: Creates a compressed image optimized for distribution.

Testing the Disk Image

After creating the .dmg, it's crucial to test it by mounting the disk image and running the application to ensure everything works as expected.

Debugging Launch Issues

During initial testing, a common issue encountered was macOS preventing the app from opening, citing an inability to check for malicious software. This was resolved by:

Instructing Users on Right-click Opening: Guiding users to right-click (or control-click) the app and select "Open" from the context menu, which presents an option to bypass the warning.
Considering Notarization for Future Releases: To further streamline the user experience, notarizing the application with Apple would eliminate this warning altogether, although it involves joining the Apple Developer Program.

Conclusion

Converting the CR2toJPG converter .app to a .dmg was a critical step in making the application easily distributable and user-friendly for macOS users. This process not only enhanced the application's professionalism but also ensured that users could install the software with confidence and ease.