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Re: NSNotification and NSRunLoop

From: Richard Frith-Macdonald
Subject: Re: NSNotification and NSRunLoop
Date: Wed, 29 Oct 2003 06:18:51 +0000

On Wednesday, October 29, 2003, at 01:29 AM, Yen-Ju Chen wrote:


 I try to send NSNotification via NSDistributedNotificationCenter to
 a GNUstep tool which use while(...){} to keep alive.
I notice that all the NSNotification reach the tool after the while loop stop.
 Why does it happen ?
Do I have to use NSRunLoop in order to receive NSNotification in the middle of while loop ?

Yes ... events only arrive while a run loop is running ... so you need to run the runloop
within your while loop.

 How to do that ?
 Something like this ?

 while (...) {

   [[NSRunLoop currentLoop] runUntilDate: [NSData distantFuture]];


Then how far the [NSData distantFuture] would be ? More than one second ?

I would recommend using -runMode:beforeDate: ne each time round the loop, unlike -runUntilDate:, this method processes the runloop only once before returning
cntrol to you while loop.

As to the date ... you probably don't want -distantFuture as thats a long way ahead (not in our lifetime). I'd guess that you want a date a fraction of a second in the future, so you can execute the other code in your while loop frequently. You should create and destroy an autorelease pool each time round the loop, to avoid running out of memory because you create a date object each time round the loop.
while (1)
[[NSRunLoop currentRunLoop] runMode: NSDefaultRunLoopMode beforeDate:
      [NSDate dateWithTimeIntervalSinceNow: 0.1]];
    // Your other code here

If, on the other hand, your while loop contains no other code, and is intended to run forever, you could just do [[NSRunLoop currentRunLoop] run] in place
of the entire while loop.

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