Igor Kulman

Detecting click on a specific NSTableViewCell

· Igor Kulman

When you use NSTableView in an macOS application, there is no direct way to know a specific NSTableViewCell was clicked by the user. In my Localization Editor project I wanted the user to be able to focus a NSTextField when clicking anywhere in the NSTableViewCell it is contained in, so I had to implement it myself.

I created a new delegate extending the NSTableViewDelegate with one additional method informing about a NSTableViewCell getting clicked

protocol NSTableViewClickableDelegate: NSTableViewDelegate {
    func tableView(_ tableView: NSTableView, didClickRow row: Int, didClickColumn: Int)
}

Then I added an extension to the NSTableView to compute the index of the clicked NSTableViewCell

extension NSTableView {
    open override func mouseDown(with event: NSEvent) {
        let localLocation = self.convert(event.locationInWindow, to: nil)
        let clickedRow = self.row(at: localLocation)
        let clickedColumn = self.column(at: localLocation)

        super.mouseDown(with: event)

        guard clickedRow >= 0, clickedColumn >= 0, let delegate = self.delegate as? NSTableViewClickableDelegate else {
            return
        }

        delegate.tableView(self, didClickRow: clickedRow, didClickColumn: clickedColumn)
    }
}

To be able to use this extension you just need to implement NSTableViewClickableDelegate instead of NSTableViewDelegate and use the additional method it provides.

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