How programmatically select a specific annotation in Mapkit - Swift

Question

I'm developing a map in MapKit/Swift 4 where i have a lot of annotations. User could select with a Picker View what annotation (just 1) he wants, and the annotation will be called (as if he had pushed on it). If it's easier, we could consider to change the color of this annotation point. The key point is to highlight this particular annotation among a lot of annotations.

After some search, i ve found this function

func selectAnnotation(_ annotation: MKAnnotation, animated: Bool)

I've implemented this following function :

func selectPoints() {
    print("selectPoints called")
    let annotation1 = MKPointAnnotation()
    annotation1.coordinate = CLLocationCoordinate2D(latitude: 48.8596833, longitude: 2.3988939)
    annotation1.title = "Temple"
    annotation1.subtitle = "\(annotation1.coordinate.latitude), \(annotation1.coordinate.longitude)"
    mapView.addAnnotation(annotation1)

    mapView.selectAnnotation(annotation1, animated: true)
}

So it's working if i create a new annotation, but how could i select previous annotations points ? But i don't have any idea or hint to go forward.

Thanks for you help.

EDIT: Part of code to input annotations.

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
    if let annotation = annotation as? Artwork {

        let reuseId = "pin"
        var pinView = mapView.dequeueReusableAnnotationView(withIdentifier: reuseId)

        if pinView == nil {
            pinView = MKAnnotationView(annotation: annotation, reuseIdentifier: reuseId)
            pinView!.canShowCallout = true
            pinView!.isDraggable = false
            pinView!.calloutOffset = CGPoint(x: 0, y: 0)
            pinView!.rightCalloutAccessoryView = UIButton(type: .detailDisclosure) as UIView

        }
        else {
            pinView!.annotation = annotation
        }

    }

    return nil
}

Presumably, you've already added annotations to the map view, is this correct? Just call the above function, passing one of your annotations as the argument. — dalton_c, Jan 03 '18 at 21:40
yes indeed. But that's my point. How could i passing one of my annotation ? What reference do i need to use ? Actually, i m looking for an example. — Hugo75, Jan 03 '18 at 21:44
Will you post some of your code, such as the code you use to add annotations, or your picker code? — dalton_c, Jan 03 '18 at 21:58

score 4 · Accepted Answer · answered Jan 03 '18 at 23:37

4

You can do this with the annotations property of your mapView. As a rough outline, in your view controller you would have some code like this:

func beginAnnotationSelection() {
    self.view.addSubview(self.pickerView)
}

func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return self.mapView.annotations.count
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return self.mapView.annotations[row].title ?? "No title"
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    self.mapView.selectAnnotation(self.mapView.annotations[row], animated: true)
}

Note that this assumes that mapView and pickerView are instance variables of your view controller, and that the picker view's data source and delegate are set to your view controller. I don't do any frame setup for the picker view or anything, so you'll have to implement all that yourself.

answered Jan 03 '18 at 23:37

Jumhyn

6,687
9
48
76

Great ! Thx. Why do i need func beginAnnotationSelection() ? – Hugo75 Jan 04 '18 at 20:04
That function is just a placeholder for whatever in your app is triggering the appearance of the picker view. It’s not necessary for the actual functionality. – Jumhyn Jan 04 '18 at 20:05
! I just was finding a way to do it !! – Hugo75 Jan 04 '18 at 20:51
any idea to sort by alphabetical the annotations ? – Hugo75 Jan 04 '18 at 22:23
You can use `Array.sort` with a custom comparison closure. Look at Apple’s docs for how to do this. – Jumhyn Jan 05 '18 at 18:34

How programmatically select a specific annotation in Mapkit - Swift

1 Answers1