MacOs - NSTableView, editing single cell

Did you define the delegate (and dataSource) for the tableView ? You can do this in IB.

Could you try:

@IBAction func cellWasEdited(_ sender : NSTextField) { 
    print("cell was edited") 
}

Of course, first disconnect the IBAction, modify and reconnect. And do a Clean Build Folder.

And the class conforms to NSTextFieldDelegate.

Here is a case:

class DataEditWindowController: NSWindowController, NSWindowDelegate, NSTableViewDelegate, NSTableViewDataSource, NSTextFieldDelegate {

I do not understand where you defined the action as Editable Action: Sent on End Editing. I do not find Sent on End Editing for MacOS (exists on iOS).

Here is my setup:

I'm using a cell based NSTableView.

Posting code in the comment area gives weird formatting…

Here it is properly edited:

import Cocoa

class ViewController: NSViewController, NSTableViewDelegate, NSTableViewDataSource { 
    var infoForTableView : [String] = ["one", "two", "three", "four", "five"]
     
     override func viewDidLoad() {
          super.viewDidLoad()
          // Do any additional setup after loading the view.
     }
     
     override var representedObject: Any? {
          didSet {
               // Update the view, if already loaded.
          }
     }
     
     @IBAction func cellWasEdited(_ sender: NSTextFieldCell) {
          print("cell was edited")
          print(sender.stringValue)
     }
     
     func numberOfRows(in tableView: NSTableView) -> Int {
          return infoForTableView.count
     }
     
     func tableView(_ tableView: NSTableView, objectValueFor tableColumn: NSTableColumn?, row: Int) -> Any? {
          return infoForTableView[row]
     }
     
}

I wonder if you have to set some binding ? Looked here but did not find the answer for cell-based: h t t p s : / / forums.bignerdranch.com/t/data-source-challenge-making-table-view-editable/7330/10

I'm using a cell based NSTableView.

You should better read this old article:

Programmatically Editing Data in an NSCell-Based Table

Seems you need to implement tableView(_:setObjectValue:for:row:) in your NSTableViewDataSource:

    func tableView(_ tableView: NSTableView, setObjectValue object: Any?, for tableColumn: NSTableColumn?, row: Int) {
        guard let stringValue = object as? String else {
            return
        }
        //Check `tableColumn` in a real implementation...
        print("cell was edited")
        print(stringValue)
        infoForTableView[row] = stringValue
    }

Generally, NSCell-based table view is sort of an older part of NSTableView, it is simpler in many simple cases, but less customizable.