SimpleTextEditorApp (STEA), a basic text editor as a native macOS app using Swift and SwiftUI, includes standard macOS app functionalities like file handling, menu bar integration, and basic text editing features.

A native macOS text editor using Swift, incorporating both SwiftUI for the modern user interface and AppKit for advanced text editing capabilities. The application will feature standard macOS functionalities—such as file handling, a menu bar, and basic text editing—and include enhancements like Markdown preview, autosave, custom menus, syntax highlighting, line numbers, and export options.

A native macOS app should support opening, editing, and saving text files, with a standard menu bar including File, Edit, Window, and Help options. SwiftUI is ideal for the interface, and since it’s a document-based app, DocumentGroup will handle file operations seamlessly.

Core Features: Document-based file handling, syntax highlighting (Highlightr), Markdown preview, autosave, custom menus, native find bar, line numbers, and export options (HTML, PDF, Markdown, RTF).

1. SimpleTextEditorApp.swift: The main app entry point, defining the document-based scene. Uses DocumentGroup to create a document-based app, initializing new documents with TextDocument and displaying them in ContentView.

2. TextDocument.swift: A struct conforming to FileDocument to manage text content and file I/O. Conforms to FileDocument, supporting plain text files (UTType.plainText). It reads from and writes to files using UTF-8 encoding.

3. ContentView.swift: The primary view containing a TextEditor for text input. Features a TextEditor bound to the document’s text, with a minimum window size and a toolbar showing the character count.

• Document-Based Architecture: Supports plain text, Markdown, Swift, Python, and shell scripts.

• Syntax Highlighting: Powered by Highlightr with customizable themes.

• Markdown Preview: Renders Markdown in a split view.

• Autosave: Saves changes every 5 seconds, toggled in settings.

• Custom Menus: Includes "Text" and "Export" options with shortcuts.

• Native Find Bar: Built into NSTextView.

• Line Numbers: Displayed in a gutter.

• Export Options: HTML, PDF, Markdown, and RTF formats.

• Performance: Debounced highlighting for efficiency.

To run this code, add the following via Swift Package Manager:

• Highlightr: https://github.com/raspu/Highlightr.git (for syntax highlighting).

• Down: https://github.com/johnxnguyen/Down.git (for Markdown rendering).

SimpleTextEditor/
├── SimpleTextEditor.xcodeproj/           # Xcode project directory
│   ├── project.pbxproj                   # Xcode project configuration
│   └── xcshareddata/
│       └── xcschemes/
│           └── SimpleTextEditor.xcscheme # Build scheme for the app
├── Sources/                              # Source code for the main app
│   ├── Models/                           # Data models and related logic
│   │   └── TextDocument.swift            # Document model for file handling
│   ├── Views/                            # SwiftUI views for the UI
│   │   ├── ContentView.swift             # Main editor UI with text editor and preview
│   │   ├── SettingsView.swift            # Settings UI for user preferences
│   │   └── CodeTextView.swift            # NSTextView wrapper for advanced text editing
│   ├── Utilities/                        # Helper classes and functions
│   │   ├── CloudSyncManager.swift        # Manages iCloud synchronization
│   │   ├── Linter.swift                  # Rule-based linter for syntax checking
│   │   └── FileTypeDetector.swift        # Detects file types and languages (new)
│   ├── App/                              # App entry point and configuration
│   │   └── SimpleTextEditorApp.swift     # Main app entry point
│   └── Extensions/                       # Swift extensions for reusability
│       └── String+Extensions.swift       # String utility extensions (new)
├── Assets.xcassets/                      # Asset catalog for images and icons
│   ├── AppIcon.appiconset/               # App icon for macOS
│   │   └── Contents.json
│   ├── Images/                           # Custom images (e.g., toolbar icons)
│   │   └── Contents.json
│   └── Colors/                           # Custom colors (e.g., for UI theming)
│       └── Contents.json
├── Resources/                            # Additional resources (e.g., sample files)
│   └── sample.swift                      # Sample Swift file for theme preview
├── Tests/                                # Unit and UI tests
│   ├── UnitTests/
│   │   ├── TextDocumentTests.swift       # Tests for TextDocument model
│   │   ├── LinterTests.swift             # Tests for linter logic
│   │   └── CloudSyncManagerTests.swift   # Tests for iCloud sync (new)
│   └── UITests/
│       └── SimpleTextEditorUITests.swift # UI tests for the editor (new)
├── Documentation/                        # Project documentation
│   ├── README.md                         # Project overview and setup instructions
│   ├── CHANGELOG.md                      # Tracks version changes
│   └── ARCHITECTURE.md                   # Describes app architecture (new)
├── Scripts/                              # Build and utility scripts
│   └── format-code.sh                    # Script for code formatting (e.g., swift-format) (new)
├── Package.swift                         # Swift Package Manager configuration (optional)
├── .gitignore                            # Git ignore file for build artifacts
├── .swiftlint.yml                        # SwiftLint configuration for code style (new)
├── Info.plist                            # App metadata and permissions
├── SimpleTextEditor.entitlements         # Entitlements for sandbox and iCloud
└── LICENSE                               # License file (e.g., MIT) (new)

• Ensure support for .txt, .md, .sh, .swift, .py

• Add iCloud capabilities

• Enable App Sandbox with User Selected File (Read/Write) and iCloud capabilities in Xcode

• Customizes the menu bar with File commands and adds "Text" and "Export" menus.

• Uses notifications to trigger actions in ContentView.

• Includes a Settings scene for user preferences.

• Added a CloudSyncManager as a @StateObject to handle iCloud synchronization, passed to ContentView and SettingsView via environmentObject

• Supports multiple file types and detects the language for syntax highlighting.

• Stores autosave and theme settings in UserDefaults.

• Added iCloudSyncKey for enabling/disabling iCloud sync.

• Synced autosaveEnabled, highlightrTheme, and iCloudSyncEnabled with NSUbiquitousKeyValueStore for iCloud persistence.

• Manages iCloud synchronization for documents and settings.

• Uses NSMetadataQuery to monitor iCloud Drive for supported file types.

• Syncs settings (autosave, theme, iCloud sync) via NSUbiquitousKeyValueStore.

• Uses CodeTextView (below) for editing with syntax highlighting.

• Shows a Markdown preview toggle for .md files using the Down library.

• Implements autosave with a 5-second timer, configurable via settings.

• Provides export functions using NSSavePanel and AppKit utilities.

• Added lintErrors state to display linting issues in the toolbar.

• Calls Linter.lint on text changes to perform syntax checking.

• Wraps NSTextView for syntax highlighting (via Highlightr), line numbers, and a native find bar.

• Debounces highlighting updates to optimize performance.

• Supports font size adjustments and theme changes via notifications.

• Provides basic linting rules for Swift (semicolons), Python (indentation), Bash (quotes), and Markdown (headers).

• Returns error messages with line numbers for display in the UI.

• Provides a settings panel to toggle autosave and select Highlightr themes.

• Updates the editor’s appearance when the theme changes.

• Added iCloudSyncEnabled toggle, disabled if iCloud is unavailable.

• Included ThemePreviewView to show a sample Swift code snippet with the selected Highlightr theme.

1. Add Highlightr and Down via Swift Package Manager.

2. Configure iCloud capabilities in Xcode (entitlements and Info.plist).

3. Ensure the app sandbox allows file read/write and iCloud access.

• Theme Preview: Open the Settings window (Cmd+,), select different themes, and verify the preview updates.

• Clickable Line Numbers: Click line numbers in the gutter, confirm the cursor jumps to the correct line with a brief highlight.

• Syntax Checking: Create files with intentional errors (e.g., missing semicolon in Swift, incorrect indentation in Python), verify errors appear in the toolbar and lines are underlined.

• Cloud Sync: Enable iCloud sync, save a document, and check if it appears in iCloud Drive on another device. Change settings and verify they sync.

• Existing Features: Confirm Markdown preview, autosave, native find bar, export options (HTML, PDF, Markdown, RTF), and syntax highlighting work as expected.