Q:

Foreach statement cannot operate on variables of type "?"

I have the following piece of code:
using (var sessionManager = GetDefaultAudioSessionManager2(DataFlow.Render))
{
    using (var sessionEnumerator = sessionManager.GetSessionEnumerator())
    {
        foreach (var session in sessionEnumerator)
        {
         //Code
        }
    }
}

But I get an error saying 

Foreach statement cannot operate on variables of type "?"

How can I fix this problem?

A:

as the name implies sessionEnumerator is an IEnumerator but foreach requires IEnumerable. here is the alternative of foreach statement.
using (var sessionManager = GetDefaultAudioSessionManager2(DataFlow.Render))
{
    while(sessionEnumerator.MoveNext())
    {
        var session = sessionEnumerator.Current;

        // Code
    }
}

