Delegates in swift?

Question

How does one go about making a delegate, i.e. NSUserNotificationCenterDelegate in swift?

Answer 1

DELEGATES IN SWIFT 2

I am explaining with example of Delegate with two viewControllers.In this case, SecondVC Object is sending data back to first View Controller.

Class with Protocol Declaration

protocol  getDataDelegate  {
    func getDataFromAnotherVC(temp: String)
}


import UIKit
class SecondVC: UIViewController {

    var delegateCustom : getDataDelegate?
    override func viewDidLoad() {
        super.viewDidLoad()
     }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    @IBAction func backToMainVC(sender: AnyObject) {
      //calling method defined in first View Controller with Object  
      self.delegateCustom?.getDataFromAnotherVC("I am sending data from second controller to first view controller.Its my first delegate example. I am done with custom delegates.")
        self.navigationController?.popViewControllerAnimated(true)
    }

}

In First ViewController Protocol conforming is done here:

class ViewController: UIViewController, getDataDelegate

Protocol method definition in First View Controller(ViewController)

func getDataFromAnotherVC(temp : String)
{
  // dataString from SecondVC
   lblForData.text = dataString
}

During push the SecondVC from First View Controller (ViewController)

let objectPush = SecondVC()
objectPush.delegateCustom = self
self.navigationController.pushViewController(objectPush, animated: true)