Network reachability with Combine and Alamofire

Hello dear readers.

In this story, I will show you how to use Combine and Alamofire together to implement a network reachability helper.

NetworkReachabilityHelper

It is possible to check network access in Swift using several different methods. I used the Alamofire NetworkReachabilityManager.
It can be replaced with anything else you prefer.

As a first step, I create a test project and add Alamofire as a dependency.
Next, I create a class:

import Alamofire
import Combine
final class NetworkReachabilityHelper {
}

Next, we will create an object from NetReachabilityManager* and a variable to publish network changes

private enum Constants {
   static let host = "google.com"
}
var reachability = NetworkReachabilityManager(host: Constants.host)
let networkStatus = PassthroughSubject<NetworkReachabilityManager.NetworkReachabilityStatus, Error>()

We just need to add two methods to begin and stop listening to network changes for the helper to be ready.

func startListening() {
    reachability?.startListening { [weak self] status in
        self?.networkStatus.send(status)
    }
}
func stopListening() {
    reachability?.stopListening()
}

This is it, we now have a helper for monitoring network status with combine.

We can add some methods to simplify our use case, for example, I created three methods for my use case

var isReachableOnCellular: Bool {
    get {
        return reachability?.isReachableOnCellular ?? false
    }
}
var isReachableOnEthernetOrWiFi: Bool {
    get {
        return reachability?.isReachableOnEthernetOrWiFi ?? false
    }
}
var isReachable: Bool {
    get {
        return reachability?.isReachable ?? false
    }
}

The final implementation is

import Alamofire
import Combine
final class NetworkReachabilityHelper {
static let shared = NetworkReachabilityHelper()
private enum Constants {
    static let host = "api1.\(Environment.domain)"
}
let networkStatus = PassthroughSubject<NetworkReachabilityManager.NetworkReachabilityStatus, Error>()
var reachability = NetworkReachabilityManager(host: Constants.host)
var isReachableOnCellular: Bool {
    get {
        return reachability?.isReachableOnCellular ?? false
    }
}
var isReachableOnEthernetOrWiFi: Bool {
    get {
        return reachability?.isReachableOnEthernetOrWiFi ?? false
    }
}
var isReachable: Bool {
    get {
        return reachability?.isReachable ?? false
    }
}
func startListening() {
    reachability?.startListening { [weak self] status in
        self?.networkStatus.send(status)
    }
}
func stopListening() {
    reachability?.stopListening()
}
deinit {
    stopListening()
}
}

and also you can find it here.

This helper can be used by subscribing to the networkStatus variable as shown in the following example,

NetworkReachabilityHelper.shared.networkStatus
.removeDuplicates()
.sink(receiveCompletion: { _ in }, receiveValue: { [weak self] value in
    \\\ check status
})
.store(in: &cancelBag)

or by accessing its methods directly,

NetworkReachabilityHelper.shared.isReachable

Hopefully you will find it useful and you can use it in your project. I’d appreciate feedback on it.