STTextView Annotations Plugin

Installation

Add the plugin package as a dependency of your application, then register/add it to the STTextView instance:

import STAnnotationsPlugin

@MainActor
class AnnotationDataSource: STAnnotationsDataSource {

    // Optional. Default implementation provided.
    // func textView(_ textView: STTextView, viewForLineAnnotation lineAnnotation: any STLineAnnotation, textLineFragment: NSTextLineFragment, proposedViewFrame: CGRect) -> NSView? {
    //    // view for annotation
    // }

    var textViewAnnotations: [any STLineAnnotation] = []
}

let dataSource = AnnotationDataSource()

// Implement AnnotationsDataSource protocol to provide annotations
let plugin = STAnnotationsPlugin(dataSource: dataSource)

// Add/register the plugin in the STTextView instance
textView.addPlugin(plugin)

Add annotations to textViewAnnotations, then call reloadAnnotations() to lay out their views. The plugin lays out only the annotations inside the viewport, and keeps their locations in step as the document is edited; an annotation whose text is deleted moves to the start of the edit.

STAnnotationsDataSource is @MainActor, and its default view implementation gives each annotation a button that removes it from textViewAnnotations. Implement textView(_:viewForLineAnnotation:textLineFragment:proposedViewFrame:) to draw something else.

Check the Demo application (AppKit or UIKit) for a reference implementation.