Unsubscribing event from inside another event

Question

I`m trying to unsubscribe from an event inside another event and I don't have a clue how I should approach this or if there is a simple pattern for this. I already looked in the official Documentation from Microsoft but I did not found anything to solve my problem.

        private void bTrainingD_Click(object sender, RoutedEventArgs e)
        {
            System.Windows.Threading.DispatcherTimer timer = new System.Windows.Threading.DispatcherTimer();
            timer.Interval = TimeSpan.FromSeconds(1);
            timer.Tick += new EventHandler(dispatcherTimer_Tick);
            timer.Start();
        }

        ...

        private void dispatcherTimer_Tick(object sender, EventArgs e)
        {
            if (true)
            {
                //some code here
            }
            else
            {
                // unsubscribe or stop the Tick-Event here
            }

        }

Thanks for your help. :-)

Answer 1

you need to keep reference to timer in a class field, not in local variable, to make it accessible in another class method:

private System.Windows.Threading.DispatcherTimer timer;

private void bTrainingD_Click(object sender, RoutedEventArgs e)
{
    timer = new System.Windows.Threading.DispatcherTimer();
    timer.Interval = TimeSpan.FromSeconds(1);
    timer.Tick += dispatcherTimer_Tick;
    timer.Start();
}

private void dispatcherTimer_Tick(object sender, EventArgs e)
{
    if (true)
    {
        //some code here
    }
    else
    {
        timer.Tick -= dispatcherTimer_Tick;
    }
}