Wait some seconds without blocking UI execution

Question

I would like to wait some seconds between two instruction, but WITHOUT blocking the execution.

For example, Thread.Sleep(2000) it is not good, because it blocks execution.

The idea is that I call a method and then I wait X seconds (20 for example) listening for an event coming. At the end of the 20 seconds I should do some operation depending on what happened in the 20 seconds.

Answer 1

Omar's solution is decent* if you cannot upgrade your environment to .NET 4.5 in order to gain access to the async and await APIs. That said, there here is one important change that should be made in order to avoid poor performance. A slight delay should be added between calls to Application.DoEvents() in order to prevent excessive CPU usage. By adding

Thread.Sleep(1);

before the call to Application.DoEvents(), you can add such a delay (1 millisecond) and prevent the application from using all of the cpu cycles available to it.

private void WaitNSeconds(int seconds)
{
    if (seconds < 1) return;
    DateTime _desired = DateTime.Now.AddSeconds(seconds);
    while (DateTime.Now < _desired) {
         Thread.Sleep(1);
         System.Windows.Forms.Application.DoEvents();
    }
}

*See https://blog.codinghorror.com/is-doevents-evil/ for a more detailed discussion on the potential pitfalls of using Application.DoEvents().