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Hi, Andrew —

The answer to your question depends somewhat on whether your text field is editable or not.

If the text field is not editable, it’s pretty straightforward — since NSTextField inherits from NSControl, it has a mouseDown(_:) method. By default a non-editable NSTextField does not respond to mouse clicks, but it’s easy to write a subclass that does:

class ClickableTextField: NSTextField {
    override func mouseDown(with event: NSEvent) {
        self.sendAction(self.action, to: self.delegate)
    }
}

(I’ve used self explicitly here to call out the method and properties that are already present on an NSControl.)

Once you have this class in your code, you can create an NSTextField in Interface Builder, change its class to ClickableTextField in the Identity Inspector, and then set up a class to act as the delegate of the NSTextField and implement an action method. Typically this would be a controller class already in your app (perhaps the window controller for the window that contains your text field). Then assign the delegate and action properties of the text field in Interface Builder, and you’re done.

If the text field is intended to be editable, then things get more complicated. In this case, the NSTextField already responds to a mouse down event by setting up the field editor — a single NSTextView shared among all the text fields in a window. Once the text field is active, all the mouse clicks go to the NSTextView as part of the editing session. If it’s actually your intention to monitor these mouse clicks, then you probably have a lot more work to do (for a sense of how much, see the Apple documentation for the Cocoa text architecture, specially the section titled “Working with the Field Editor”). I would suggest considering what your actual goal is; if you find yourself fighting with AppKit, there’s usually a different/better way to accomplish your goal.

Hope this helps. Thanks for dropping by.