在超类符合该协议的子类中实现委托方法Swift

Question

I have incorporated the GoogleMaps API into my app and all is well with that. However after a bit more development I realized I will need to have two different ViewControllers, both showing a GMSMapView but each having slightly different functionality. I decided to make a base class which has the common functionality and that base class conforms to GMSMapViewDelegate . In this base class, among other things I have:

class BaseMapViewController: UIViewController {

    var mapView = GMSMapView()

    override func viewDidLoad() {
        super.viewDidLoad()
        mapView.delegate = self

        loadMap()
    }

    func loadMap() {
        mapView = GMSMapView(frame: CGRectZero)
        mapView.mapType = kGMSTypeHybrid
        self.view = mapView
    }
}

extension BaseMapViewController: GMSMapViewDelegate {}

One of the subclasses needs to implement func mapView(mapView: GMSMapView!, didTapAtCoordinate coordinate: CLLocationCoordinate2D) so I just implement that in the subclass (shown below), but it doesn't register any taps.

class SellerMapViewController: BaseMapViewController {

    override func viewDidLoad(){
        super.viewDidLoad()
    }

    func mapView(mapView: GMSMapView!, didTapAtCoordinate coordinate: CLLocationCoordinate2D) {
        print("\(coordinate.latitude,coordinate.longitude)")
    }
}

I then tried putting that delegate method in the base class and it still didn't register any taps. Any ideas as to what I am doing wrong or what I could try?

Thanks!

Answer 1

It sounds like there could be a couple things going on:

• Make sure you are setting the superclass as the delegate, not just conforming to the protocol.
• I have done a similar things in my own code, and what I do is implement a dummy function in the superclass that if called prints a message that its subclass needs to implement it, so that the superclass fully implements the delegate method.
• Implement the methods that you need to in your subclass. If the relationship was properly set up in your superclass, the methods will be called in your subclass, overriding the same call in the superclass.