Swift MKMapView.setRegion not working after MKLocalSearch.Request - ios

Question

I've been working on an app to annotate an MKMapView with all nightlife locations near a user. I have implemented a recenter function that is called by a SwiftUI button. The recenter works fine based on CLLocationManager.location, but after any MKLocalSearch query, the setRegion stops working. It must be the setRegion because the correct lat/long are still printed. I also know it is not due to the annotations because the same bug happens when the annotation add/remove part is commented out. Does it possibly have something to do with linking the searchRequest.region and map.region? manager is the CLLocationManager instance, map is the MapView
func recenter(){
print("Recenter called")
guard let center = manager.location?.coordinate else{
print("Could not get location for recenter")
return
}
let newRegion = MKCoordinateRegion(center: center, latitudinalMeters: 1000, longitudinalMeters: 1000)
print("\(center.latitude) and \(center.longitude)")
map.setRegion(newRegion, animated: true)
}
func queryAndAnnotate(){
let searchRequest = MKLocalSearch.Request()
searchRequest.naturalLanguageQuery = "nightlife"
searchRequest.region = map.region
let search = MKLocalSearch(request: searchRequest)
search.start{response, error in
guard let response = response else {
Alert(title:Text("Alert"), message: Text("Error: \(error?.localizedDescription ?? "Unknown Error")"))
return
}
var mapItemPlacemarks: [MKPointAnnotation] = []
self.barsList = []
for i in response.mapItems{
let x = MKPointAnnotation()
x.coordinate = i.placemark.coordinate
x.title = i.name
mapItemPlacemarks.append(x)
}
self.map.removeAnnotations(mapItemPlacemarks)
self.map.addAnnotations(mapItemPlacemarks)
}
}

Answer 1

MKLocalSearch.start calls the completionHandler in background task.
In this handler you are updating your mapView instance in background task.
Make sure to call all update methods of mapView in main task (removeAnnotations, addAnnotations, setRegion)
btw in
self.map.removeAnnotations(mapItemPlacemarks)
self.map.addAnnotations(mapItemPlacemarks)
you are removing mapItemPlacemarks that do not exist in the mapView. This makes no sense, but it is not your problem.

Answer 2

As it turns out the problem was coming from a dynamic update to a ScrollView. The ScrollView was within a slide up drawer that sat above the MapView on the Z axis. When the ScrollView was updated with the results from the local search, the MapView object lost track of userLocation (read 0,0) and the region could not be programmatically changed. I ended up fixing the problem by ditching the recenter() function altogether and instead implementing an MKUserTrackingButton within its own UIViewRepresentable (for SwiftUI). The MKUserTrackingButton is how the system maps cycles through user tracking modes. You can read the docs for it here: https://developer.apple.com/documentation/mapkit/mkusertrackingbutton