Get Data From Async Completion Handler - swift

Question

Trying to get name of a city, while having latitude and longitude.
Inside a model class Location, I'm using reverseGeocodeLocation(location: , completionHandler: ) func that comes with CLGeocoder (part of CoreLocation).
func getLocationName() {
let geoCoder = CLGeocoder()
let location = CLLocation(latitude: currentLatitude, longitude: currentLongitude)
geoCoder.reverseGeocodeLocation(location, completionHandler: { placemarks, error in
guard let addressDict = placemarks?[0].addressDictionary else {
return
}
if let city = addressDict["City"] as? String {
self.currentCity = city
print(city)
}
if let zip = addressDict["ZIP"] as? String {
print(zip)
}
if let country = addressDict["Country"] as? String {
print(country)
}
})
}
However, in ViewController, after running the getLocationName(), the location.currentCity is nil, since the completion handler is async, and wasn't finished yet.
How can I make sure that the completion handler is finished running so I can access location.currentCity ?

Answer 1

Pass a closure as a function parameter in your getLocationName which
you can call inside the reverseGeocodeLocation closure.
func updateLocation(currentCity : String) -> Void
{
print(currentCity)
}
func getLocationName(callback : #escaping (String) -> Void)
{
let geoCoder = CLGeocoder()
let location = CLLocation(latitude: currentLatitude, longitude: currentLongitude)
geoCoder.reverseGeocodeLocation(location, completionHandler: { placemarks, error in
guard let addressDict = placemarks?[0].addressDictionary else {
return
}
if let city = addressDict["City"] as? String
{
self.currentCity = city
callback(city)
print(city)
}
if let zip = addressDict["ZIP"] as? String {
print(zip)
}
if let country = addressDict["Country"] as? String {
print(country)
}
})
}
In your ViewController...
getLocationName(callback: updateLocation)

Answer 2

I would create a function where location.currentCity is used, and call this function from the completion handler
So if your code looks like:
func foo() {
var location
getLocationName()
print(location.currentcity) // nil
}
change it to:
func foo() {
var location
getLocationName()
}
func bar() {
print(location.currentcity) // someplace
}
and call bar() from your completion handler