Swift - Trouble with getting nil when setting values in between functions - ios

Question

Hi I seem to only be able to get nil as my location variable while I'm writing a simple location receiving class. I've searched stack overflow for a while and tried many solutions but I can't seem to fix it.
Below is my code. I'm trying to methods, one is to set the variables in a struct in my didUpdateLocations method. The other is just to update a variable userLocation. Both are just giving my nil at the moment and I can't figure out why.
class SendLocation: NSObject, CLLocationManagerDelegate{
var userLocation: CLLocation? = nil
var locationManager:CLLocationManager!
struct LocationStruct{
var latitude:CLLocationDegrees?, longitude:CLLocationDegrees?
}
var locationStruct = LocationStruct()
func sendLocationPost(){
determineCurrentLocation()
print(userLocation) // This is nil
print(locationStruct.latitude) // This is nil
print(locationStruct.longitude) // This is nil
}
func determineCurrentLocation(){
locationManager = CLLocationManager()
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.requestAlwaysAuthorization()
if CLLocationManager.locationServicesEnabled(){
locationManager.startUpdatingLocation()
}
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]){
userLocation = locations[0] as CLLocation
print(userLocation) // This IS NOT nil
locationStruct.latitude=userLocation?.coordinate.latitude
locationStruct.longitude=userLocation?.coordinate.longitude
}
Thanks in advance for the help as I know it will be something simple/silly

Answer 1

It's just a matter of understanding that things take time. You are forging ahead as if starting to get a location gives you a location instantly. But it doesn't:
func sendLocationPost(){
determineCurrentLocation()
// so now things start... but they take _time_...!
print(userLocation) // This is nil
// because it's _too soon!_
// ...
}
When you first call determineCurrentLocation, it takes a long time for the sensors to warm up and for a good location to arrive:
func determineCurrentLocation(){
locationManager = CLLocationManager()
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.requestAlwaysAuthorization()
if CLLocationManager.locationServicesEnabled(){
locationManager.startUpdatingLocation()
// SLOWLY... things now start to happen
}
}
At last, after some significant time, maybe, just maybe, we finally start to get some updates, and after some more time, maybe they are not nil:
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]){
userLocation = locations[0] as CLLocation
print(userLocation) // This IS NOT nil
locationStruct.latitude=userLocation?.coordinate.latitude
locationStruct.longitude=userLocation?.coordinate.longitude
}
Now we've got a location. But meanwhile your code in sendLocationPost ended long ago, and got nil.