Why does all formatting disappear from an NSTextView when using NSViewRepresentable and SwiftUI? - swift

Question

I am making a small program using SwiftUI that allows users to create rich text "notes" in an NSTextView. I have enabled all of the formatting features from NSTextView, including the ability to work with images. The program is only for macOS and not for iOS/iPadOS.
The problem I am facing is that whenever the user types anything in the NSTextView, the caret moves to the end and all formatting and images disappear.
Since I am just using the standard formatting options provided by Apple, I have not subclassed NSTextStorage or anything like that. My use-case should be pretty simple.
The program is tiny so far and the entire source code is on GitHub (https://github.com/eiskalteschatten/ScratchPad), but I'll post the relevant code here.
This is my NSViewRepresentable class for the NSTextView:
import SwiftUI
struct RichTextEditor: NSViewRepresentable {
#EnvironmentObject var noteModel: NoteModel
func makeNSView(context: Context) -> NSScrollView {
let scrollView = NSTextView.scrollableTextView()
guard let textView = scrollView.documentView as? NSTextView else {
return scrollView
}
textView.isRichText = true
textView.allowsUndo = true
textView.allowsImageEditing = true
textView.allowsDocumentBackgroundColorChange = true
textView.allowsCharacterPickerTouchBarItem = true
textView.isAutomaticLinkDetectionEnabled = true
textView.displaysLinkToolTips = true
textView.isAutomaticDataDetectionEnabled = true
textView.isAutomaticTextReplacementEnabled = true
textView.isAutomaticDashSubstitutionEnabled = true
textView.isAutomaticSpellingCorrectionEnabled = true
textView.isAutomaticQuoteSubstitutionEnabled = true
textView.isAutomaticTextCompletionEnabled = true
textView.isContinuousSpellCheckingEnabled = true
textView.usesAdaptiveColorMappingForDarkAppearance = true
textView.usesInspectorBar = true
textView.usesRuler = true
textView.usesFindBar = true
textView.usesFontPanel = true
textView.importsGraphics = true
textView.delegate = context.coordinator
context.coordinator.textView = textView
return scrollView
}
func updateNSView(_ nsView: NSScrollView, context: Context) {
context.coordinator.textView?.textStorage?.setAttributedString(noteModel.noteContents)
}
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
class Coordinator: NSObject, NSTextViewDelegate {
var parent: RichTextEditor
var textView : NSTextView?
init(_ parent: RichTextEditor) {
self.parent = parent
}
func textDidChange(_ notification: Notification) {
guard let _textView = notification.object as? NSTextView else {
return
}
self.parent.noteModel.noteContents = _textView.attributedString()
}
}
}
On GitHub: https://github.com/eiskalteschatten/ScratchPad/blob/main/ScratchPad/Notes/RichTextEditor.swift
And this is my NoteModel class responsible for managing the NSTextView content:
import SwiftUI
import Combine
final class NoteModel: ObservableObject {
private var switchingPages = false
#Published var pageNumber = UserDefaults.standard.value(forKey: "pageNumber") as? Int ?? 1 {
didSet {
UserDefaults.standard.set(pageNumber, forKey: "pageNumber")
switchingPages = true
noteContents = NSAttributedString(string: "")
openNote()
switchingPages = false
}
}
#Published var noteContents = NSAttributedString(string: "") {
didSet {
if !switchingPages {
saveNote()
}
}
}
private var noteName: String {
return "\(NoteManager.NOTE_NAME_PREFIX)\(pageNumber).rtfd"
}
init() {
openNote()
}
private func openNote() {
// This is necessary, but macOS seems to recover the stale bookmark automatically, so don't handle it for now
var isStale = false
guard let bookmarkData = UserDefaults.standard.object(forKey: "storageLocationBookmarkData") as? Data,
let storageLocation = try? URL(resolvingBookmarkData: bookmarkData, options: .withSecurityScope, relativeTo: nil, bookmarkDataIsStale: &isStale)
else {
ErrorHandling.showErrorToUser("No storage location for your notes could be found!", informativeText: "Please try re-selecting your storage location in the settings.")
return
}
let fullURL = storageLocation.appendingPathComponent(noteName)
let options = [NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.rtfd]
do {
guard storageLocation.startAccessingSecurityScopedResource() else {
ErrorHandling.showErrorToUser("ScratchPad is not allowed to access the storage location for your notes!", informativeText: "Please try re-selecting your storage location in the settings.")
return
}
if let _ = try? fullURL.checkResourceIsReachable() {
let attributedString = try NSAttributedString(url: fullURL, options: options, documentAttributes: nil)
noteContents = attributedString
}
fullURL.stopAccessingSecurityScopedResource()
} catch {
print(error)
ErrorHandling.showErrorToUser(error.localizedDescription)
}
}
private func saveNote() {
// This is necessary, but macOS seems to recover the stale bookmark automatically, so don't handle it for now
var isStale = false
guard let bookmarkData = UserDefaults.standard.object(forKey: "storageLocationBookmarkData") as? Data,
let storageLocation = try? URL(resolvingBookmarkData: bookmarkData, options: .withSecurityScope, relativeTo: nil, bookmarkDataIsStale: &isStale)
else {
ErrorHandling.showErrorToUser("No storage location for your notes could be found!", informativeText: "Please try re-selecting your storage location in the settings.")
return
}
let fullURL = storageLocation.appendingPathComponent(noteName)
do {
guard storageLocation.startAccessingSecurityScopedResource() else {
ErrorHandling.showErrorToUser("ScratchPad is not allowed to access the storage location for your notes!", informativeText: "Please try re-selecting your storage location in the settings.")
return
}
let rtdf = noteContents.rtfdFileWrapper(from: .init(location: 0, length: noteContents.length))
try rtdf?.write(to: fullURL, options: .atomic, originalContentsURL: nil)
fullURL.stopAccessingSecurityScopedResource()
} catch {
print(error)
ErrorHandling.showErrorToUser(error.localizedDescription)
}
}
}
On GitHub: https://github.com/eiskalteschatten/ScratchPad/blob/main/ScratchPad/Notes/NoteModel.swift
Does anyone have any idea why this is happening and/or how to fix it?
I have found these similar issues, but they don't really help me much:
Replacing NSAttributedString in NSTextStorage Moves NSTextView Cursor - I don't have any custom syntax highlighting or anything like that.
Cursor always jumps to the end of the UIViewRepresentable TextView when a newline is started before the final line + after last character on the line - Only solves the caret issue and causes jerky scroll behavior in longer documents.
Edit: I forgot to mention that I'm using macOS Ventura, but am targeting 12.0 or higher.
Edit #2: I have significantly updated the question to reflect what I've found through more debugging.