public MainViewModel(IContactsViewModel contactsViewModel, IContactDetailViewModel contactDetailViewModel)
{
ContactsViewModel = contactsViewModel;
CurrentViewModel = contactsViewModel;
ContactsViewModel.NewContactRequested += OnNewContactRequested;
ContactsViewModel.EditContactRequested += OnContactEditRequested;
ContactDetailViewModel = contactDetailViewModel;
ContactDetailViewModel.CancelRequested += OnCancelSaveContactRequested;
ContactDetailViewModel.SaveCompleted += OnSaveCompleted;
}
