macOS File Converter App

I’m building a simple-to-use macOS application that lets users drag-and-drop a file, pick a new format, and instantly download the converted version. At launch the app must:

• Accept uploads in PDF, DOCX, JPEG or other supported format
• Export to PDF, DOCX, PNG or other supported format
• Run fully on macOS (Monterey and above) with a clean, native Swift/SwiftUI/developer suggestion interface
• Perform the conversion locally or via a lightweight API—whichever you recommend for speed, accuracy, and security

Here’s what I need from you:

1. A functional prototype that handles the input types and produces the output types without data loss.
2. An intuitive format-selection step (I’m flexible on dropdowns, radio buttons, or another elegant solution).
3. Clear error handling for unsupported files or failed conversions.
4. Build instructions plus concise inline code comments so I can maintain future formats.
5. A short README outlining third-party libraries or command-line tools you choose (e.g., PDFKit, DocX, ImageMagick).

If you’re comfortable packaging the app for the Mac App Store, let me know—code-signing and notarization expertise will be a bonus but aren’t strict launch requirements.

I’m ready to move quickly and will be responsive with feedback. Let me see examples of similar utilities you’ve shipped, and tell me which approach you’d take for reliable, high-quality conversions.