How to know which NSCombobox selector calling the Delegate

I have the following code written in SWIFT for OS X App, the code is working fine (NSComboBox are select able only, not editable)

I have these two IBOutlet projNewProjType and projNewRouter, when I change the the selection of either of the NSComboBox, I can see the correct selected Index value and String value but how to check that the returned Index value is from projNewProjType NOT projNewRouter in the comboBoxSelectionDidChange()

import Cocoa
class NewProjectSetup: NSViewController, NSComboBoxDelegate {
  let comboxProjValue: [String] = [“No”,”Yes”]
  let comboxRouterValue: [String] = ["No","Yes"]

  @IBOutlet weak var projNewProjType: NSComboBox!
  @IBOutlet weak var projNewRouter: NSComboBox!


  @IBAction func btnAddNewProject(sender: AnyObject) {
    print(“Add New Button Pressed!”)
  }

  @IBAction func btnCancel(sender: AnyObject) {
    self.dismissViewController(self)
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    addComboxValue(comboxProjValue,projNewProjType)
    addComboxValue(comboxRouterValue,projNewRouter)

    self.projNewProjType.selectItemAtIndex(0)
    self.projNewRouter.selectItemAtIndex(0)

    self.projNewProjType.delegate = self
    self.projNewRouter.delegate = self
  }


  func comboBoxSelectionDidChange(notification: NSNotification) {
    let comboBox: NSComboBox = (notification.object as? NSComboBox)!

    print("comboBox comboBox: \(comboBox)")
    /* This printed “<NSComboBox: 0x6000001e1a00>”*/

    print("comboBox objectValueOfSelectedItem: \(comboBox.objectValueOfSelectedItem)")
    /* This printed the correct selected String value */

    print("comboBox indexOfSelectedItem: \(comboBox.indexOfSelectedItem)")
    /* This printed the correct selected Index value */        
  }

  /* Add value to Combo box */
  func addComboxValue(myVal:[String],myObj:AnyObject){
    let myValno: Int = myVal.count
    for i in 0..<myValno{
        myObj.addItemWithObjectValue(myVal[i])
    }
  }
}

You can set identifiers to your NSComboBoxes in IB. Select your combo box and choose identity inspector and name identifier. Then you are able to do like this:

if comboBox.identifier == "someIdentifier" {
    // Do something
}