Passing data from a query to mapView viewForAnnotation function - ios

Question

I am trying to display custom pins on an MKMapView. These pins will have a custom image as well as a UILabel that will display a value.
I was able to successfully create the custom pin, with label. Right now the label displays a static value. I queried the data from a backend service like parse, and saved the data for each point. That way when the user taps on a certain point i can display the data in the viewController, however I am not sure how to pass this data from my query method into the didSelectAnnotation and viewForAnnotation methods.
I also would like to change the static value that the label shows to one queried from the server. I tried to do this by creating a class called CustomPointAnnotation, which inherits from MKPointAnnotation and has an initializer with three properties. these properties are set during the query, so how can I access these properties in the mapViewDidSelectAnnotationView, and the viewForAnnotation functions so that I can use the data for my needs. (for things like setting the text for a label within the viewController to a property of that specific annotation).
Below is an image that shows the viewController and what I have so far:
Here is the custom point class:
class CustomPointAnnotation: MKPointAnnotation {
var price: String!
var streetName: String!
var ratingValue: Int!
init?(price: String, streetName: String, ratingValue: Int) {
self.price = price
self.streetName = streetName
self.ratingValue = ratingValue
super.init()
}
}
Below is the query that I run in viewDidLoad:
func displayPoints() {
let pointsQuery = PFQuery(className: "testLocation")
let currentLocation = PFGeoPoint(location: locationManager.location)
pointsQuery.whereKey("location", nearGeoPoint: currentLocation, withinMiles: 2)
pointsQuery.findObjectsInBackgroundWithBlock { (points, error) -> Void in
if error == nil {
print("number of spots: \(points?.count)")
let spots = points! as [PFObject]
for pinPoint in spots {
let point = pinPoint["location"] as! PFGeoPoint
let price = String(pinPoint["price"])
let ratingValue = pinPoint["rating"] as! Int
let streetName = "Park Street, San Francisco CA"
self.customAnnotation = CustomPointAnnotation(price: price, streetName: streetName, ratingValue: ratingValue)
//// PRINT DATA OBTAINED FOR TESTING PURPOSES///////////////////////////////////////////////////////////
print(self.customAnnotation.price)
print(self.customAnnotation.streetName)
print(self.customAnnotation.ratingValue)
///////////////////////////////////////////////////////////////////////////////////////////////////////
self.customAnnotation!.coordinate = CLLocationCoordinate2DMake(point.latitude, point.longitude)
self.priceArray.append(pinPoint["price"])
self.customAnnotation!.price = pinPoint["price"] as? String
self.mapView.addAnnotation(self.customAnnotation!)
}
} else {
JSSAlertView().danger(self, title: "something went wrong", text: "error: \(error)")
}
}
}
here is the didSelectAnnotationView:
func mapView(mapView: MKMapView, didSelectAnnotationView view: MKAnnotationView) {
//var anot: MKAnnotation
if ((view.annotation?.isKindOfClass(MKUserLocation)) != nil){
view.image = nil
}
for anot in mapView.annotations {
print(mapView.annotations.count)
let annotationView = mapView.viewForAnnotation(anot)
if (annotationView != nil) {
annotationView?.image = UIImage(named: "pin")
priceLabel.textColor = UIColor.whiteColor()
}
//priceLabel.textColor = UIColor.blueColor()
view.image = UIImage(named: "pinselected")
print("image changed")
}
}
and finally the viewForAnnotation method:
func mapView(mapView: MKMapView, viewForAnnotation annotation: MKAnnotation) -> MKAnnotationView? {
if annotation.isKindOfClass(MKUserLocation){
return nil
}
if !(annotation is CustomPointAnnotation) {
print("all custom images added")
return nil
}
let reuseID = "identifier"
var annotationView = mapView.dequeueReusableAnnotationViewWithIdentifier(reuseID)
if annotationView == nil {
annotationView = CustomAnnotationView(annotation: annotation, reuseIdentifier: reuseID, price: "13" )
annotationView?.canShowCallout = false
} else {
annotationView?.annotation = annotation
}
//let cpa = annotation as! CustomPointAnnotation
//let annotationView = CustomAnnotationView(annotation: annotation, reuseIdentifier: nil, price: "11")
//annotationView!.addSubview(priceLabel)
annotationView?.annotation = annotation
annotationView?.image = UIImage(named: "pin.png")
return annotationView
}

Answer 1

You can down cast in swift with the as operator. In didSelectAnnotationView the annotationView has an annotation property. Your custom annotation view will have your custom annotation as its annotation property, so you can attempt to down cast it to your subclass by saying:
if let annotation = view.annotation as? CustomPointAnnotation
Assuming that's possible, you will then have access to your subclass's properties.
func mapView(mapView: MKMapView, didSelectAnnotationView view: MKAnnotationView) {
//var anot: MKAnnotation
if ((view.annotation?.isKindOfClass(MKUserLocation)) != nil){
view.image = nil
}
for anot in mapView.annotations {
print(mapView.annotations.count)
let annotationView = mapView.viewForAnnotation(anot)
if (annotationView != nil) {
annotationView?.image = UIImage(named: "pin")
priceLabel.textColor = UIColor.whiteColor()
}
//priceLabel.textColor = UIColor.blueColor()
}
view.image = UIImage(named: "pinselected")
if let annotation = view.annotation as? CustomPointAnnotation
{
self.priceLabel.text = annotation.price //for example
//update the rest of your UI
}
print("image changed")
}
Similarly in viewForAnnotation you can down cast the MKAnnotation to CustomPointAnnotation and MKAnnotationView to CustomAnnotationView.
func mapView(mapView: MKMapView, viewForAnnotation annotation: MKAnnotation) -> MKAnnotationView? {
if annotation.isKindOfClass(MKUserLocation){
return nil
}
if !(annotation is CustomPointAnnotation) {
print("all custom images added")
return nil
}
let reuseID = "identifier"
let cpa = annotation as! CustomPointAnnotation
var annotationView = mapView.dequeueReusableAnnotationViewWithIdentifier(reuseID) as! CustomAnnotationView
if annotationView == nil {
annotationView = CustomAnnotationView(annotation: cpa, reuseIdentifier: reuseID, price: cpa.price)
annotationView?.canShowCallout = false
} else {
annotationView?.annotation = cpa
annotationView?.price = cpa.price
}
annotationView?.image = UIImage(named: "pin.png")
return annotationView
}
Your CustomAnnotationView should update its price label when its price is set by implementing price's didSet.