Reverse geocoding in Swift 4

CLGeocoder methods are asynchronous. What you would need a completion handler:

import UIKit
import CoreLocation
import PlaygroundSupport
PlaygroundPage.current.needsIndefiniteExecution = true

---

func geocode(latitude: Double, longitude: Double, completion: @escaping (_ placemark: [CLPlacemark]?, _ error: Error?) -> Void)  {
    CLGeocoder().reverseGeocodeLocation(CLLocation(latitude: latitude, longitude: longitude)) { placemark, error in
        guard let placemark = placemark, error == nil else {
            completion(nil, error)
            return
        }
        completion(placemark, nil)
    }
}

or simply:

func geocode(latitude: Double, longitude: Double, completion: @escaping (_ placemark: [CLPlacemark]?, _ error: Error?) -> Void)  {
    CLGeocoder().reverseGeocodeLocation(CLLocation(latitude: latitude, longitude: longitude), completionHandler: completion)
}

or extending CLLocation:

extension CLLocation {
    func geocode(completion: @escaping (_ placemark: [CLPlacemark]?, _ error: Error?) -> Void) {
        CLGeocoder().reverseGeocodeLocation(self, completionHandler: completion)
    }
}

---

To format your placemark as a mailing address you can use Contacts framework CNPostalAddressFormatter:

import Contacts

extension Formatter {
    static let mailingAddress: CNPostalAddressFormatter = {
        let formatter = CNPostalAddressFormatter()
        formatter.style = .mailingAddress
        return formatter
    }()
}

extension CLPlacemark {
    var mailingAddress: String? {
        postalAddress?.mailingAddress
    }
}

extension CNPostalAddress {
    var mailingAddress: String {
        Formatter.mailingAddress.string(from: self)
    }
}

---

placemark

Contains an array of CLPlacemark objects. For most geocoding requests,
this array should contain only one entry. However, forward-geocoding
requests may return multiple placemark objects in situations where the
specified address could not be resolved to a single location. If the
request was canceled or there was an error in obtaining the placemark
information, this parameter is nil.

For more information about the CLPlacemark properties you can check this CLPlacemark

---

Usage:

let location = CLLocation(latitude: -22.963451, longitude: -43.198242)
location.geocode { placemark, error in
    if let error = error as? CLError {
        print("CLError:", error)
        return
    } else if let placemark = placemark?.first {
        // you should always update your UI in the main thread
        DispatchQueue.main.async {
            //  update UI here
            print("name:", placemark.name ?? "unknown")
            
            print("address1:", placemark.thoroughfare ?? "unknown")
            print("address2:", placemark.subThoroughfare ?? "unknown")
            print("neighborhood:", placemark.subLocality ?? "unknown")
            print("city:", placemark.locality ?? "unknown")
            
            print("state:", placemark.administrativeArea ?? "unknown")
            print("subAdministrativeArea:", placemark.subAdministrativeArea ?? "unknown")
            print("zip code:", placemark.postalCode ?? "unknown")
            print("country:", placemark.country ?? "unknown", terminator: "\n\n")
            
            print("isoCountryCode:", placemark.isoCountryCode ?? "unknown")
            print("region identifier:", placemark.region?.identifier ?? "unknown")
    
            print("timezone:", placemark.timeZone ?? "unknown", terminator:"\n\n")

            // Mailind Address
            print(placemark.mailingAddress ?? "unknown")
        }
    }
}

---

This will print

name: Morro da Saudade
address1: Rua Casuarina
address2: 597
neighborhood: Lagoa
city: Rio de Janeiro
state: RJ
subAdministrativeArea: unknown
zip code: 22011-040
country: Brazil

isoCountryCode: BR
region identifier: <-22.96345100,-43.19824200> radius 141.83
timezone: America/Sao_Paulo (current)

Rua Casuarina, 597
Lagoa
Rio de Janeiro RJ
22011-040
Brazil