How to make NSSpellChecker work with NSDocument? - macos

Question

I have a core data / document-driven macOS app, using Swift and I struggle on combining the out-of-the-box spell checking API with an NSDocument (NSPersistentDocument in my case)
It took me more time than it should take, but this is what I got, mostly guided by this great answer:
class VTDocument: NSPersistentDocument, NSChangeSpelling {
[...]
private let spellchecker = SpellChecker()
#IBAction func showGuessPanel(_ sender: Any?){
spellchecker.startSpellCheck(nodes: Array(db.nodes), tag: 0)
}
#IBAction #objc func changeSpelling(_ sender: Any?){
spellchecker.replace(with: "Test")
}
This is leading me to see the NSSpellChecker.spellingPanel, correctly showing the word to correct. However, the changeSpelling function should be "called" by the panel but is never called. The above spellChecker is a simple wrapper around the NSSpellChecker that keeps the status between function calls.
The SpellChecker class looks like this.
import Cocoa
class SpellChecker {
let checker = NSSpellChecker.shared
let count: UnsafeMutablePointer<Int> = UnsafeMutablePointer<Int>.allocate(capacity: 1)
var nodes = Array<Node> ()
var nodeNr = 0
var stringPos = 0
var range: NSRange = NSRange()
func startSpellCheck(nodes: [Node], tag: Int ) {
self.nodes = nodes
nodeNr = 0
stringPos = 0
continueChecking()
}
func continueChecking(){
if nodes.count == 0 {
return
}
if nodeNr >= nodes.count {
checker.updateSpellingPanel(withMisspelledWord: "")
checker.spellingPanel.orderFront(self)
return
}
if let nodeText = nodes[nodeNr].label {
range = checker.checkSpelling(of: nodeText, startingAt: stringPos, language: nil, wrap: false, inSpellDocumentWithTag: 0, wordCount: count)
if count.pointee > 0 {
stringPos = range.lowerBound
checker.updateSpellingPanel(withMisspelledWord: nodeText[range])
checker.spellingPanel.orderFront(self)
return
}
}
nodeNr = nodeNr + 1
continueChecking()
}
func replace(with: String){
if let nodeText = nodes[nodeNr].label {
let text = nodeText as NSString
text.replacingCharacters(in: range, with: with)
nodes[nodeNr].label = text as String
}
}
}