Ensure TK2 only for BaseTextView

README.md

@@ -25,8 +25,9 @@ targets: [
 
 ## BaseTextView
 
-This is an `NSTextView` subclass that aims for an absolute minimal amount of changes. Things are allowed only if they are required for correct functionality. It is intended to be a drop-in replacement for `NSTextView`, and should maintain compatibilty with existing subclasses. Behaviors are appropriate for all types of text.
+This is an TextKit 2-only `NSTextView` subclass that aims for an absolute minimal amount of changes. Things are allowed only if they are required for correct functionality. It is intended to be a drop-in replacement for `NSTextView`, and should maintain compatibilty with existing subclasses. Behaviors are appropriate for all types of text.
 
+- Disables all support for TextKit 1
 - Workaround for `scrollRangeToVisible` bug (FB13100459)
 - Minimum `textContainerInset` enforcement to address more `scrollRangeToVisible` bugs
 - Additional routing to `NSTextViewDelegate.textView(_:, doCommandBy:) -> Bool`:  `paste`, `pasteAsRichText`, `pasteAsPlainText`

Sources/BaseTextView/BaseTextView.swift

@@ -5,7 +5,9 @@ import OSLog
 // I guess this should be defined by AppKit, but isn't
 fileprivate let NSOldSelectedCharacterRanges = "NSOldSelectedCharacterRanges"
 
-/// A minimal `NSTextView` subclass to support correct functionality.
+/// A minimal `NSTextView` subclass to support correct functionality using TextKit 2.
+///
+/// - Warning: TextKit 1 is **unsupported**. An attempt to access the `layoutManager` property will assert in debug.
 @available(macOS 12.0, *)
 open class BaseTextView: NSTextView {
 	public typealias OnEvent = (_ event: NSEvent, _ action: () -> Void) -> Void
@@ -23,7 +25,20 @@ open class BaseTextView: NSTextView {
 	public var continuousSelectionNotifications: Bool = false
 
 	public override init(frame frameRect: NSRect, textContainer container: NSTextContainer?) {
-		super.init(frame: frameRect, textContainer: container)
+		let effectiveContainer = container ?? NSTextContainer()
+
+		if effectiveContainer.textLayoutManager == nil {
+			let textLayoutManager = NSTextLayoutManager()
+
+			textLayoutManager.textContainer = effectiveContainer
+
+			let storage = NSTextContentStorage()
+
+			storage.addTextLayoutManager(textLayoutManager)
+			storage.primaryTextLayoutManager = textLayoutManager
+		}
+
+		super.init(frame: frameRect, textContainer: effectiveContainer)
 
 		self.textContainerInset = CGSize(width: 5.0, height: 5.0)
 	}
@@ -36,6 +51,12 @@ open class BaseTextView: NSTextView {
 	public required init?(coder: NSCoder) {
 		fatalError("init(coder:) has not been implemented")
 	}
+
+	public override var layoutManager: NSLayoutManager? {
+		assertionFailure("TextKit 1 is not supported by this type")
+
+		return nil
+	}
 }
 
 @available(macOS 12.0, *)

Tests/BaseTextViewTests/BaseTextViewTests.swift

@@ -11,6 +11,12 @@ final class MockTextViewDelegate: NSObject, NSTextViewDelegate {
 
 @MainActor
 final class BaseTextViewTests: XCTestCase {
+	func testUsesTextKit2ByDefault() {
+		let view = BaseTextView()
+
+		XCTAssertNotNil(view.textLayoutManager)
+	}
+
 	func testStockMissingDoCommandBy() {
 		let view = NSTextView()
 		let delegate = MockTextViewDelegate()