Swift 3 Protocol Pattern Snippet

Swift 3 Protocol Pattern Snippet

// set up - MapViewController is the parent.  A ContainerView is used to place the UI for directions - part of the DirectionsViewController.
// The DirectionsViewController has a protocol method for letting the delegate know when a user has tapped the 'get directions' button and passes the to and from data

// this ViewController is the delegate for the DirectionsViewController
Class MapViewController: UIViewController, DirectionsViewControllerDelegate {

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        
        // for getting access to the DirectionsViewController and settings its delegate as THIS controller
        if segue.identifier == segueIdToDirectionsVC {
            
            if let destinationVC = segue.destination as? DirectionsViewController {
                
                destinationVC.delegate = self
            }
        }
    }  

    func didRequestDirections(locations: (from: String, to: String)) {
        
        print("user tapped - get directions | to: \(locations.from) and from: \(locations.to)")
        
    }
}

....

protocol DirectionsViewControllerDelegate: class {
    
    func didRequestDirections(locations: (from: String, to: String))
}

class DirectionsViewController: UIViewController {

    weak var delegate: DirectionsViewControllerDelegate?
    
    @IBOutlet weak var fromTextField: UITextField!
    @IBOutlet weak var toTextField: UITextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }

    // MARK: - Directions    
    @IBAction func handleDirectionsButtonTap(_ sender: Any) {
  
        if let fromText = fromTextField.text, let toText = toTextField.text {
            
            delegate?.didRequestDirections(locations: (from: fromText, to: toText))
        }
    }
}