问Swift 3协议和代理方法？

EN

import UIKit

class ViewController: UIViewController, PinRemoverDelegate {

    func removePin() {
        mapView.removeAnnotation(selectedAnnotation)
    }

}

import UIKit

protocol PinRemoverDelegate: class {
   func removePin()
   }

class SecondViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    weak var delegate: PinRemoverDelegate? = nil

    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
        if editingStyle == .delete {
            let place = storedLocations[indexPath.row]
            context.delete(place)
            (UIApplication.shared.delegate as! AppDelegate).saveContext()

    // Attempt To remove The Pin
        delegate?.removePin()
        }

        tableView.reloadData()
    }

}