Location-related Kotlin extension functions for Android.

android-kotlin-location-extensions.kt

// Location-related Kotlin extension properties for Android.
// They must be implemented in an Activity because Geocoder needs a context.
// Or else, they must be turned from extension properties to extension functions that receive a context as parameter.


// Example of use
// Use case: show the user his locality name on a TextView
val userLocation = Location(someLatitude, someLongitude)
launch(UI) {
    aTextView.text = userLocation.localityName.await()
}

// Returns list of addresses of a given LatLng. Uses Kotlin Coroutines. Does networking - don't use getFromLocation on UI thread.
// private because you probably want other higher-level values (e.g. LatLng.localityName)
private val LatLng.getAddresses: Deferred<List<Address>?>
    get() = async {
        try {
            Geocoder(this@MainActivity, Locale.getDefault()).getFromLocation(latitude, longitude, 1)
        } catch (_: IOException) {
            null
        }
    }

// Returns a locality name (most commonly, a city name) given a LatLng. Uses Kotlin Coroutines.
val LatLng.localityName: Deferred<String?>
    get() = async { getAddresses.await()?.firstOrNull()?.locality }

// Returns an ISO 3166 country code given a LatLng. Uses Kotlin Coroutines.
val LatLng.countryCode: Deferred<String?>
    get() = async { getAddresses.await()?.firstOrNull()?.countryCode }

// Returns the country name given a LatLng. Uses Kotlin Coroutines.
val LatLng.countryName: Deferred<String?>
    get() = async { getAddresses.await()?.firstOrNull()?.countryName }

// Converts Location object to LatLng object
val Location.latLng
    get() = LatLng(latitude, longitude)

// Avoids having to call location.latLng.localityName - instead call location.localityName
val Location.localityName: Deferred<String?>
    get() = latLng.localityName

// Avoids having to call location.latLng.countryCode - instead call location.countryCode
val Location.countryCode: Deferred<String?>
    get() = latLng.countryCode

// Avoids having to call location.latLng.countryName - instead call location.countryName
val Location.countryName: Deferred<String?>
    get() = latLng.countryName

Why do you create two coroutines, while you can use one?

private val LatLng.getAddresses: List<Address>?
    get() = ...

val LatLng.localityName: Deferred<String?>
    get() = async { getAddresses?.firstOrNull()?.locality }

@dmytrodanylyk your approach works, but if you would use getAddresses directly, you’d get an exception (networking on UI thread)

Async on getAddresses makes it safe. This safety makes up (for me) for the very small overhead of creating an extra unnecessary coroutine.

github full working?