NSTextView AppKit, custom subclass of NSTextBlock bug

custom-nstextblock-bug.swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        NativeEditor()
            .frame(maxWidth: 400, maxHeight: 600)
    }
}

struct NativeEditor: NSViewRepresentable {
    typealias NSViewType = NSTextView
    
    func makeNSView(context: Context) -> NSTextView {
        let textView = NSTextView()
        textView.textStorage?.append(NSAttributedString(string: "\n"))
        textView.textStorage?.append(NSAttributedString(string: "\n"))
        textView.textStorage?.append(NSAttributedString(string: "\n"))
        let style1 = NSMutableParagraphStyle()
        style1.textBlocks = [CodeBlock()]
        
        textView.textStorage?.append(NSAttributedString(string: "Hello world 1\n", attributes: [
            NSAttributedString.Key.paragraphStyle: style1
        ]))
        
        textView.textStorage?.append(NSAttributedString(string: "\n"))
        textView.textStorage?.append(NSAttributedString(string: "\n"))
        textView.textStorage?.append(NSAttributedString(string: "\n"))
        
        return textView
    }
    
    func updateNSView(_ nsView: NSTextView, context: Context) {}
}

class CodeBlock: NSTextBlock {
    override init() {
        super.init()
        setValue(100, type: .percentageValueType, for: .width)
        backgroundColor = NSColor(white: 0.6, alpha: 1.0)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}