Incorrect rendering when using NSTextView with TextKit 1

Question

I encountered some issues with rendering in NSTextView. When I'm hitting enter the last line rendering is lagging and the line is not visible. Also, sometimes when I hit backspace the last line is temporarily duplicated.

The problem is presented on the video: here.

Code to reproduce the issue:

    func bug() {
        let textContainer = NSTextContainer()
        textContainer.widthTracksTextView = true
        textContainer.heightTracksTextView = true

        let layoutManager = NSLayoutManager()
        let textStorage = NSTextStorage(string: "")

        layoutManager.addTextContainer(textContainer)
        textStorage.addLayoutManager(layoutManager)

        let textView = NSTextView(frame: .zero, textContainer: textContainer)
        textView.autoresizingMask = [.width, .height]

        // The case that presents the bug:
        textView.string = "\naaaaa\nbbbbbb"
        textView.setSelectedRange(.init(location: 0, length: 0))

        let scrollView = NSScrollView()
        scrollView.documentView = textView
        scrollView.translatesAutoresizingMaskIntoConstraints = false

        view.addSubview(scrollView)

        NSLayoutConstraint.activate([
            scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            scrollView.topAnchor.constraint(equalTo: view.topAnchor),
            scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
    }

In general, it looks like it is a problem with TextKit 1. If I use TextKit 2, it works fine:

    func textKit2NoBug() {
        let textView = NSTextView(usingTextLayoutManager: true)
        textView.autoresizingMask = [.width, .height]

        // The case that presents the bug:
        textView.string = "\naaaaa\nbbbbbb"
        textView.setSelectedRange(.init(location: 0, length: 0))

        let scrollView = NSScrollView()
        scrollView.documentView = textView
        scrollView.translatesAutoresizingMaskIntoConstraints = false

        view.addSubview(scrollView)

        NSLayoutConstraint.activate([
            scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            scrollView.topAnchor.constraint(equalTo: view.topAnchor),
            scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
    }

However, in my case, I have to rely on TextKit 1. Does anyone know how to workaround this issue?

Full source code: here

Incorrect rendering when using NSTextView with TextKit 1

0 Answers0