Make button programmatically and add programmatic control with event

MapViewController.swift

import UIKit
import MapKit
import CoreLocation

class MapViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {
  
  var mapView: MKMapView!
  let locationManager =  CLLocationManager()
    
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        let location = locations[0]
        
        let span:MKCoordinateSpan = MKCoordinateSpanMake(0.01, 0.01) // set scale factor
        let myLocation: CLLocationCoordinate2D = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
        let region:MKCoordinateRegion = MKCoordinateRegionMake(myLocation, span)
        mapView.setRegion(region, animated: true)
        mapView.showsUserLocation = true
        locationManager.stopUpdatingLocation() // This is for toggling otherwise locationManager will keep tracking in focus
   }
  
   override func loadView() {
      // Create a MapView
      mapView = MKMapView()
      
      // set it as *the* view of this view controller
      view = mapView
     
      // Button for current Location
      let currentLocation = UIButton(frame: CGRect(x:10, y: 200, width: 50, height: 30))
      currentLocation.backgroundColor = UIColor.blue
      view.addSubview(currentLocation)
      currentLocation.addTarget(self, action: #selector(self.getLocation(_:)), for: .touchUpInside)
      
   }
  
   override func viewDidLoad() {
        super.viewDidLoad()
        
        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.requestWhenInUseAuthorization()
        
   }
    
   func getLocation(_ sender: UIButton) {
        locationManager.startUpdatingLocation()
   }

}