public void RemoveListener(IPickerObserver observer)
{
bool success = _observers.Remove(observer);
if (!success)
{
throw new Exception("Can not remove observer");
}
}
public void AddListener(IPickerObserver observer)
{
bool alreadyExist = _observers.Any(o => o == observer);
if (alreadyExist)
{
throw new Exception("This observer already registered");
}
_observers.Add(observer);
}