Xcode Swift - How to ask the user display their pin from a UI button

Question

Created May ’21

Replies 1

Boosts 0

Participants 2

I'm new Xcode swift and I'm trying to let the user press a button to display the pin (custom annotation in this case) in the map but I'm not sure how to do it.

Here's the code so far:

import CoreLocation

import MapKit

import UIKit

class ViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate {



@IBOutlet var mapView: MKMapView!



let manager = CLLocationManager()

override func viewDidLoad() {

super.viewDidLoad()



}

override func viewDidAppear( animated: Bool) {

super.viewDidAppear(animated)

manager.desiredAccuracy = kCLLocationAccuracyBest

manager.delegate = self

manager.requestWhenInUseAuthorization()

manager.startUpdatingLocation()

}



func locationManager( manager: CLLocationManager, didUpdateLocations locations: [CLLocation]){

if let location = locations.first{

manager.stopUpdatingLocation()



render(location: location)

}

}



func render(location: CLLocation){



let coordinate = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)



let span = MKCoordinateSpan(latitudeDelta: 0.1, longitudeDelta: 0.1)



let region = MKCoordinateRegion(center: coordinate, span: span)



mapView.setRegion(region, animated: true)



let pin = MKPointAnnotation()

pin.coordinate = coordinate

pin.title = "COVID-19 Case"

pin.subtitle = "There is COVID-19 cases in your area. "

mapView.addAnnotation(pin)





}



func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {

guard !(annotation is MKUserLocation) else{

return nil

}



var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: "custom")



if annotationView == nil {

//Create the view

annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: "custom")



annotationView?.canShowCallout = true

}

else{

annotationView?.annotation = annotation

}



annotationView?.image = UIImage(named: "viruscase")



return annotationView



}



}

Any help would be appreciated.

Boost

Answer 1

Claude31 OP

May ’21

I noted some errors in the following:
you need to add the underscore before manager

Code Block     func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]){

The same for viewDidAppear:

Code Block     override func viewDidAppear( _ animated: Bool) {

I edited your code to format it without all the extra empty lines and used the code formatter (<>):

Code Block import CoreLocation
import MapKit
import UIKit
class ViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate {
    @IBOutlet var mapView: MKMapView!
    let manager = CLLocationManager()
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    override func viewDidAppear( _ animated: Bool) {
        super.viewDidAppear(animated)
        manager.desiredAccuracy  = kCLLocationAccuracyBest
        manager.delegate = self
        manager.requestWhenInUseAuthorization()
        manager.startUpdatingLocation()
    }
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]){
        if let location = locations.first{
            manager.stopUpdatingLocation()
            render(location: location)
        }
    }
    func render(location: CLLocation){
        let coordinate = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
        let span = MKCoordinateSpan(latitudeDelta: 0.1, longitudeDelta: 0.1)
        let region = MKCoordinateRegion(center: coordinate, span: span)
        mapView.setRegion(region, animated: true)
        let pin = MKPointAnnotation()
        pin.coordinate = coordinate
        pin.title = "COVID-19 Case"
        pin.subtitle = "There is COVID-19 cases in your area. "
        mapView.addAnnotation(pin)
    }
    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
        guard !(annotation is MKUserLocation) else {
            return nil
        }
        var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: "custom")
        if annotationView == nil {
            //Create the view
            annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: "custom")
            annotationView?.canShowCallout = true
        } else {
            annotationView?.annotation = annotation
        }
        annotationView?.image = UIImage(named: "viruscase")
        return annotationView
    }
}

To show / hide annotations, create an IBAction for the button and remove or add annotations.
Create a var to keep status (are annotations visible).

Here is an example from https://stackoverflow.com/questions/31266837/show-hide-annotation-when-button-is-pressed
You'll have to adapt to your annotation set: only one annotation ?
The simplest would be to keep annotation parameters in a property of the class and use it in addAttractionPins

Code Block var annotationIsVisible = false
@IBAction func showAnnotation(sender: AnyObject) {
    if !annotationIsVisible {
        addAttractionPins()
        annotationIsVisible = true
    }else {
        Map.removeAnnotations(Map.annotations)
        annotationIsVisible = false
    }
}
func addAttractionPins() {
    let filePath = NSBundle.mainBundle().pathForResource("Attractions", ofType: "plist")
    let attractions = NSArray(contentsOfFile: filePath!)
    for attraction in attractions! {
        let point = CGPointFromString(attraction["location"] as! String)
        let coordinate = CLLocationCoordinate2DMake(CLLocationDegrees(point.x), CLLocationDegrees(point.y))
        let title = attraction["name"] as! String
        let typeRawValue = (attraction["type"] as! String).toInt()!
        let type = AttractionType(rawValue: typeRawValue)!
        let subtitle = attraction["subtitle"] as! String
        let annotation = AttractionAnnotation(coordinate: coordinate, title: title, subtitle: subtitle, type: type)
        mapView.addAnnotation(annotation)
    }
}

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