On Sep 21, 2010, at 5:55 AM, Rafael Cerioli wrote:
> Hi,
>
> I'm trying to understand how run loops work. I've written this useless piece
> of code and I'm not sure why "success" does not show up...
> What happens is that waitUntilReady never terminates, because it seems that
> the runUntilDate in myButtonAction never ends as well.
Yes, as that is what your code is doing.
> My theory would be that calling a runUntilDate from myButtonAction
> (myButtonAction is started by a run loop observer) will just prevent other
> sources and observers in the *current* run loop's loop (or run loop's run ??)
> to be processed until myButtonAction terminates.
No--there is no "prevention" whatsoever. -runUntilDate: tells the current
runloop *specifically* to process all input sources, and to not exit until all
sources are processed *and* the specified expiration date has been reached.
> So, waitUntilReady's call to runUntilDate would prevent the end of
> myButtonAction's current run loop's loop.
>
> Does someone have more info about that ?
>
> - (void) myButtonAction {
> // A button event has been sent, waking up the run loop and calling
> that method
>
> // this will be called in 1 second
> [self performSelector:@selector(waitUntilReady) withObject:nil
> afterDelay:1];
This is an input source, so the runloop will not exit until the method exits.
> // process the current run loop during 10 seconds :
> [[NSRunLoop currentRunLoop] runUntilDate:[NSDate
> dateWithTimeIntervalSinceNow:10]];
Which never happens, as you never get to this line, because the method cannot
exit.
> [self setReady:YES];
> }
>
> - (void) waitUntilReady {
>
> while(![self isReady]) {
> // this should just process the run loop once :
> [[NSRunLoop currentRunLoop] runUntilDate:[NSDate date]];
> }
>
> NSLog(@"success!");
> }
HTH,
Keary Suska
Esoteritech, Inc.
"Demystifying technology for your home or business"
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