Save textview to CoreData when text change - swift

Question

I'm building a note-taking app for macOS and have a question about saving text whenever the user is editing the NSTextView. I use textDidChange function to detect any changes in the NSTextView and then save the changes to Core Data. However, my code will only save the first edit that the user makes, e.g. if I type hello in the NSTextView, it will only save h instead of hello.
I'm wondering how to fix it? Thank you for your help.
This is the code:
class ViewController: NSViewController, NSTextViewDelegate, NSTableViewDataSource, NSTableViewDelegate {
#IBOutlet var textArea: NSTextView!
#IBOutlet weak var noteList: NSTableView!
let context = (NSApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
var notes = [Testnote]()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
loadData()
textArea.textStorage?.setAttributedString(notes[0].noteItem!)
textArea.delegate = self
}
override var representedObject: Any? {
didSet {
// Update the view, if already loaded.
}
}
// MARK: - Tableview stuff
func numberOfRows(in tableView: NSTableView) -> Int {
return notes.count
}
func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
if let cell = tableView.makeView(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "rowNo"), owner: self) as? NSTableCellView {
cell.textField?.stringValue = "sth here"
return cell
}
return nil
}
func tableViewSelectionDidChange(_ notification: Notification) {
if noteList.selectedRow >= 0 {
let selectedNote = notes[noteList.selectedRow]
textArea.textStorage?.setAttributedString(selectedNote.noteItem!)
}
}
func textDidChange(_ notification: Notification) {
if let textview = notification.object as? NSTextView {
notes[0].noteItem = textview.attributedString()
saveData()
}
}
func loadData() {
let request: NSFetchRequest<Testnote> = Testnote.fetchRequest()
do {
notes = try context.fetch(request)
} catch {
print("sth wrong")
}
}
func saveData() {
do {
try context.save()
} catch {
print("Error saving \(error)")
}
}
#IBAction func addButton(_ sender: Any) {
// Create new NSObject and assign values
let newnote = Testnote(context: context)
newnote.noteItem = textArea.attributedString()
(NSApplication.shared.delegate as? AppDelegate)?.saveAction(nil)
}
#IBAction func delete(_ sender: NSButton) {
context.delete(notes[noteList.selectedRow])
do {
try context.save()
} catch {
print("Error")
}
}
}