Add a Nuget Reference to:

• MSharp.Framework.Api
• PushSharp

UserDevice entity

Create an entity in your project named UserDevice. It should have the following properties. For each installation a record will be inserted into this table.

• InstallationToken (string, unique, mandatory) -> This is a uniquely generated value that the mobile app will send to register the installation on a device for a particular user.
• InstallationTime (DateTime, mandatory) -> This is saved at the same time as the above property.
• User (association, optional) -> The user entity in your application
• DeviceType (string, mandatory) -> Values should be exactly one of  iOS, Android, or Windows .
• PushNotificationToken (string, optional) -> The value for this will be sent by the devices and saved via the API when they sign up for push notification.
• LastLogOff (DateTime, optional) -> Set via API as soon as the user logs off. When the user logs back in, this gets removed.

Note: It should implement: MSharp.Framework.Api.PushNotification.IUserDevice

Authentication API 

 [HttpPost, Route("push-notification/register")]
        public IHttpActionResult RegisterPushNotification(User user, string installationToken, string pushNotificationToken, string deviceType)
        {
            var device = UserDevice.FindByInstallationToken(installationToken)?.Clone() ?? new UserDevice();

            device.User = user;
            device.InstallationToken = installationToken;
            device.PushNotificationToken = pushNotificationToken;
            device.DeviceType = deviceType;
            device.InstallationTime = LocalTime.Now;
            device.LastLogOff = null;
            Database.Save(device);

            return Ok(device.PushNotificationToken);
        }

        // Unregisters user's device
        [HttpPost, Route("push-notification/unregister")]
        public IHttpActionResult UnregisterPushNotification(string installationToken)
        {
            var device = UserDevice.FindByInstallationToken(installationToken);
            if (device != null) Database.Update(device, d => d.PushNotificationToken = null);

            return Ok();
        }

Logging Off

When the user logs off from the App, it should call an API and send the installation token with it to then update the user device record.

[HttpPost, Route("logout/{installationToken}")]
public IHttpActionResult Logout(string installationToken)
{
      UserDevice.FindByInstallationToken(installationToken)?.SetDeviceAsOffline();
      return Ok();
}

--------In the UserDevice logic file ------------

public void SetDeviceAsOffline() => Database.Update(this, d => d.LastLogOff = LocalTime.Now);