NSTextView doesn't correctly redraw when deleting text and setting attribute at the same time

For some reason the code above doesn't reproduce the issue anymore. Here is new code that seems to work (for now):

class ViewController: NSViewController {

    @IBOutlet var textView: NSTextView!
    
    override func viewDidAppear() {
        textView.textContainerInset = CGSize(width: 0, height: 8)
        let _ = textView.layoutManager
        textView.textStorage!.setAttributedString(NSAttributedString(string: "1\n\n2\n3\n4"))
        textView.textStorage!.addAttribute(.foregroundColor, value: NSColor.labelColor, range: NSRange(location: 0, length: textView.textStorage!.length))
        textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 0, length: 2))
        textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 1, length: 2))
        textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 3, length: 2))
        textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 5, length: 2))

        DispatchQueue.main.asyncAfter(deadline: .now() + 1) { [self] in
            textView.selectedRange = NSRange(location: 3, length: 0)
            textView.deleteBackward(nil)
            textView.textStorage!.beginEditing()
            textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 0, length: 2))
            textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 2, length: 2))
            textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 4, length: 2))
            textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 6, length: 1))
            textView.textStorage!.endEditing()
        }
    }
    
    private func paragraphStyle(indent: Double) -> NSParagraphStyle {
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.firstLineHeadIndent = indent
        return paragraphStyle
    }

}

You are using TextKit1 (by accessing textView.layoutManager). If you can switch to TextKit2, as shown in the following code, the issue will disappear.

guard let textContextManager = textView.textLayoutManager?.textContentManager else {
    print("`textView.textLayoutManager?.textContentManager` is nil. You are still on TextKit1?")
    return
}
textView.textContainerInset = CGSize(width: 0, height: 8)
//let _ = textView.layoutManager
textContextManager.performEditingTransaction {
    textView.textStorage!.setAttributedString(NSAttributedString(string: "1\n\n2\n3\n4"))
    textView.textStorage!.addAttribute(.foregroundColor, value: NSColor.labelColor, range: NSRange(location: 0, length: textView.textStorage!.length))
    textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 0, length: 2))
    textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 1, length: 2))
    textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 3, length: 2))
    textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 5, length: 2))
}
DispatchQueue.main.asyncAfter(deadline: .now() + 1) { [self] in
    textContextManager.performEditingTransaction {
        textView.selectedRange = NSRange(location: 3, length: 0)
        textView.deleteBackward(nil)
        //textView.textStorage!.beginEditing()
        textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 0, length: 2))
        textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 2, length: 2))
        textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 4, length: 2))
        textView.textStorage!.addAttribute(.paragraphStyle, value: paragraphStyle(indent: 100), range: NSRange(location: 6, length: 1))
        //textView.textStorage!.endEditing()
    }
}

If you need to stick with TextKit1, in which case I'd be curious of why, commenting out the following line seems to work around the issue:

//textView.textContainerInset = CGSize(width: 0, height: 8)

If the intent of using a custom textContainerInset is to move the text down 8 points, you might be able to achieve it by moving textView down.

Best,
——
Ziqiao Chen
 Worldwide Developer Relations.

I'm still using TextKit1 for backwards compatibility.

If the intent of using a custom textContainerInset is to move the text down 8 points, you might be able to achieve it by moving textView down.

Yes, removing the container inset solves the issue, but I need it. Do you mean moving the scrollView down? That looks ugly. If you mean the textView inside the scrollView, how would I do that?

Did you try to insert an empty view above the text view as a sibling view (or a subview of the enclosing scrollview)? I think that should push the text view down.

Best,
——
Ziqiao Chen
 Worldwide Developer Relations.

I tried different ways, but wasn't able to find one that would still allow the text view to resize automatically according to its content. Do you have any suggestion?