tomql Quick Look Extension

macOS Quick Look extension for .toml files. Right-click any .toml file and select "Quick Look" to preview it as plain text.

Implementation Notes

Challenges Overcome

1. No standard .toml UTType: macOS doesn't export a public public.toml UTType. Solution: Created custom com.hippietrail.toml and exported it via the host app's Info.plist.

2. UTType export not working with generated Info.plist: Xcode's GENERATE_INFOPLIST_FILE = YES doesn't properly handle INFOPLIST_KEY_UTExportedTypeDeclarations arrays. Solution: Switched to manual Info-generated.plist with GENERATE_INFOPLIST_FILE = NO.

3. Extension not loading files: Initial implementation didn't read file contents. Issues were:

   • Missing NSTextView outlet connection in XIB
   • Need to explicitly wire outlets in the NIB file for QuickLook extensions
   • File read had to happen on main thread via DispatchQueue

Build & Test

xcodebuild build -scheme tomql-host-app
qlmanage -r  # Reset QuickLook daemon
qlmanage -p /path/to/file.toml

Or in Finder: Right-click .toml file → Quick Look (spacebar)

Key Files

• tomql-preview-extension/PreviewViewController.swift - Loads & displays TOML as text
• tomql-host-app/Info-generated.plist - Declares custom com.hippietrail.toml UTType
• tomql-preview-extension/Info.plist - Extension configuration
• tomql-preview-extension/Base.lproj/PreviewViewController.xib - Text view UI