<xctk:ToggleSwitch HorizontalAlignment="Left" IsChecked="{Binding IsContinue}" />

private bool _IsContinue;
public bool IsContinue
{
    get { return this._IsContinue; }
    set
    {
        if (this._IsContinue== value)
            return;

        this._IsContinue= value;
        OnPropertyChanged("IsContinue");
    }
}