Delegates in swift?

Question

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

Answer 1

Very easy step by step (100% working and tested)

step1: Create method on first view controller

 func updateProcessStatus(isCompleted : Bool){
    if isCompleted{
        self.labelStatus.text = "Process is completed"
    }else{
        self.labelStatus.text = "Process is in progress"
    }
}

step2: Set delegate while push to second view controller

@IBAction func buttonAction(_ sender: Any) {

    let secondViewController = self.storyboard?.instantiateViewController(withIdentifier: "secondViewController") as! secondViewController
    secondViewController.delegate = self
    self.navigationController?.pushViewController(secondViewController, animated: true)
}

step3: set delegate like

class ViewController: UIViewController,ProcessStatusDelegate {

step4: Create protocol

protocol ProcessStatusDelegate:NSObjectProtocol{
func updateProcessStatus(isCompleted : Bool)
}

step5: take a variable

var delegate:ProcessStatusDelegate?

step6: While go back to previous view controller call delegate method so first view controller notify with data

@IBAction func buttonActionBack(_ sender: Any) {
    delegate?.updateProcessStatus(isCompleted: true)
    self.navigationController?.popViewController(animated: true)
}

@IBAction func buttonProgress(_ sender: Any) {
    delegate?.updateProcessStatus(isCompleted: false)
    self.navigationController?.popViewController(animated: true)

}