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The translucent left column is the sidebar — the split-rectangle button toggles it
Sidebar (Source List)
/ NavigationSplitView · NSSplitViewController /
also called source list, navigation sidebar, split view sidebar
A sidebar is the leftmost navigation column used by apps such as Finder and Mail to organize destinations into sections. AppKit calls its list appearance a source list, while modern SwiftUI normally builds the structure with NavigationSplitView and sidebar list style. It can collapse independently of the main content and often uses a translucent material behind its rows.
Anatomy — every part, named
- 1Source-list style
NSTableView.Style.sourceListThe spacious, vibrancy-aware Finder-like treatment of the rows is AppKit's source-list style.
- 2Section header
NSOutlineViewDelegate.outlineView(_:isGroupItem:)The small emphasized label dividing destinations into groups such as Favorites or iCloud is a section header.
- 3Selection pill
NSTableRowView.isSelected“The rounded colored background behind the current row” is the sidebar's selection pill.
- 4Sidebar toggle toolbar button
NSSplitViewController.toggleSidebar(_:)The standard split-rectangle toolbar icon that reveals or hides the leading column is the sidebar toggle.
Prompt — paste into your agent
Build a macOS Sidebar (Source List) with NavigationSplitView (AppKit: NSSplitViewController), using the native translucent sidebar appearance and source-list row selection. It must occupy the left column, support collapsing, and keep navigation separate from the detail content.
In code
The exact names this thing goes by in code — each row is one framework’s word for it. Use the row that matches your project (or paste it into your prompt).
| SwiftUI | NavigationSplitView | |
| AppKit | NSSplitViewController | |
| AppKit | NSSplitViewItem(sidebarWithViewController:) | |
| AppKit | NSTableView.Style.sourceList | the standard AppKit list appearance |
| SwiftUI | ListStyle.sidebar |