How to get client IP address using Web Api2 .NET FRAMEWORK 4.6.2

I want to fetch client IP address using asp.net web api2 application.

I try this code but request = request ?? Request; error this line code.

the name "request" does not exist in the current context

public class GetIp
{
    public string IpFetch()
    {
        return GetClientIp();
    }

    private string GetClientIp(HttpRequestMessage request = null)
    {
        request = request ?? Request;
        if (request.Properties.ContainsKey("MS_HttpContext"))
        {
            return ((HttpContextWrapper)request.Properties["MS_HttpContext"]).Request.UserHostAddress;
        }
        else if (request.Properties.ContainsKey(RemoteEndpointMessageProperty.Name))
        {
            RemoteEndpointMessageProperty prop = (RemoteEndpointMessageProperty)request.Properties[RemoteEndpointMessageProperty.Name];
            return prop.Address;
        }
        else if (HttpContext.Current != null)
        {
            return HttpContext.Current.Request.UserHostAddress;
        }
        else
        {
            return null;
        }
    }
}

How to get client IP address?