principal
The system places the item in the principal item section.
Declaration
static let principal: ToolbarItemPlacementDiscussion
Principal actions are key units of functionality that receive prominent placement. For example, the location field for a web browser is a principal item.
In macOS and in Mac Catalyst apps, the system places the principal item in the center of the toolbar.
In iOS, iPadOS, and tvOS, the system places the principal item in the center of the navigation bar. This item takes precedent over a title specified through View/navigationTitle.