TextView.swift

//

import SwiftUI

struct MyTextEditor: NSViewRepresentable {
    @Binding var text: String

    final class Coordinator: NSObject, NSTextViewDelegate {
        var text: Binding<String>

        init(text: Binding<String>) {
            self.text = text
        }

        func textDidChange(_ notification: Notification) {
            print(notification)
            guard let t = notification.object as? NSTextView else { return }
            text.wrappedValue = t.string
//            let t = notification.userInfo
        }
    }

    func makeCoordinator() -> Coordinator {
        Coordinator(text: $text)
    }

    func makeNSView(context: Context) -> NSTextView {
        let t = NSTextView()
        t.delegate = context.coordinator
        return t
    }

    func updateNSView(_ nsView: NSTextView, context: Context) {
        context.coordinator.text = $text
        nsView.textStorage?.setAttributedString(.init(string: text, attributes: [
            .foregroundColor: NSColor.textColor
        ]))
    }

}

struct ContentView: View {
    @State var toggle = false
    @State var str1 = "Hello"
    @State var str2 = "World"
    var body: some View {
        VStack {
            Toggle(isOn: $toggle, label: { Text("Toggle") } )
            MyTextEditor(text: toggle ? $str1 : $str2)
            TextEditor(text: $str1)
            TextEditor(text: $str2)
        }
        .padding()
    }
}

#Preview {
    ContentView()
}