DefaultApp

DefaultApp is a native macOS application designed to easily manage default program associations for file extensions. It provides a clean, modern, and highly interactive user interface to view and modify which application opens specific file types globally across the system.

Key Features

• Liquid Glass UI: Designed with a high-fidelity "liquid glass" visual style, featuring floating control capsules, subtle gradient background blurs, specular highlights, and 3D-like borders.
• Global Association Management: Query and update default applications for common and custom file extensions globally using macOS system APIs (NSWorkspace and Uniform Type Identifiers).
• Intelligent App Scanner: Scans installed applications on your Mac, parses their Info.plist declarations (UTExportedTypeDeclarations and UTImportedTypeDeclarations), and automatically extracts supported file extensions.
• Custom Extensions: Allows users to manually add and manage custom file extensions that are not pre-defined.
• Polished Interactive Experience:
  • Custom Hand Cursor: Interactive elements (list rows, buttons, segmented pickers) display a pointing hand cursor on hover, which remains stable during clicks and selections.
  • Smart Focus Dismissal: Clicking outside the search bar or on empty background areas automatically dismisses keyboard/search focus.
  • Unified Title Bar: Integrated controls and traffic lights blend seamlessly into the window chrome.
• Single-Window Lifecycle: Operates as a single-window utility that automatically terminates when its main window is closed.

Technology Stack

• SwiftUI: Modern declarative UI framework.
• AppKit: For advanced system integration, including NSWorkspace for default app configuration, UTType for file type handling, and custom cursor/focus management.
• Swift 5.9+ / Observation: Utilizes the modern @Observable framework for reactive data binding.
• Target Platform: macOS 14.0+ (takes advantage of macOS 15.0+ native pointerStyle API with reliable AppKit fallbacks for older versions).

Project Structure

DefaultApp/
├── DefaultApp.swift                  # Application entry point & lifecycle delegate
├── DefaultApp.entitlements           # App security configuration (Sandbox disabled)
├── Models/
│   ├── FileTypeItem.swift            # Model representing a file extension and its UTI
│   ├── FileTypeSource.swift          # Enum representing common vs custom extensions
│   └── CommonExtensions.swift        # Pre-defined list of common macOS file extensions
├── Services/
│   ├── DefaultAppService.swift       # NSWorkspace-backed service to get/set default apps
│   ├── FileTypeCatalog.swift         # Catalog manager for scanning and saving extensions
│   └── InstalledAppExtensionScanner.swift # Scanner to extract supported UTIs from installed apps
├── Views/
│   ├── ContentView.swift             # Root split-view container
│   ├── FileTypeListView.swift        # Sidebar list with floating Liquid Glass controls
│   ├── AppPickerView.swift           # Detail panel for choosing default applications
│   ├── AddExtensionSheet.swift       # Sheet to add custom file extensions
│   ├── LiquidGlassStyle.swift        # View modifiers for glass panels and hand cursors
│   ├── SidebarToggle.swift           # Helper for programmatic sidebar toggling
│   └── FileTypeListTab.swift         # Tab enum for common vs custom extensions
└── Assets.xcassets/                  # App icon and accent color assets

How to Build and Run

Requirements

• macOS 14.0 or later
• Xcode 15.0 or later

Running in Xcode

1. Clone this repository to your local machine.
2. Open DefaultApp.xcodeproj in Xcode.
3. Select the DefaultApp scheme and a Mac run destination.
4. Press Cmd + R to build and run the application.

Building a Distributable DMG

A build script is provided in the Scripts directory to compile the application and package it into a .dmg file.

Unsigned Local Build

To build an unsigned DMG for local testing or sharing:

./Scripts/build-dmg.sh

The output DMG will be generated at build/DefaultApp.dmg.

📦 How to Install and Run Unsigned DMG (Gatekeeper Bypass)

Since the local build is unsigned and unnotarized, macOS Gatekeeper will block it by default with warnings like "App is damaged" or "Developer cannot be verified".

Please follow these steps to install and run the application:

1. Install:

   • Double-click DefaultApp.dmg.
   • Drag DefaultApp.app into the /Applications folder.

2. Bypass Security Check (Fastest - One-Line Terminal Command):

   • Open Terminal.app.
   • Run the following command (enter your Mac password if prompted):

     xattr -cr /Applications/DefaultApp.app

   • Now you can double-click and open DefaultApp normally from your Applications or Launchpad!

3. Alternative Bypass (Manual via System Settings):

   • Double-click the app in /Applications. When the warning popup appears, click Cancel.
   • Open System Settings -> Privacy & Security.
   • Scroll down to the Security section.
   • You will see a message: "DefaultApp was blocked from use because it is not from an identified developer."
   • Click Open Anyway and enter your Mac credentials.
   • Click Open on the final confirmation dialog.

Signed and Notarized Release Build

To build a signed and notarized DMG for distribution, run the script with the --release flag and provide your Apple Developer credentials:

DEVELOPMENT_TEAM=YOUR_TEAM_ID \
SIGNING_IDENTITY="Developer ID Application: Your Name (YOUR_TEAM_ID)" \
NOTARY_PROFILE=your-notary-profile-name \
./Scripts/build-dmg.sh --release

License

This project is licensed under the MIT License. See the LICENSE file for details.