Shawn,
I'm using KVO in this case as a means to only do certain processing
when a thread really exits. I start my Core Audio thread like this:
- (void)start
{
streamerThread = [[NSThread alloc] initWithTarget:self
selector:@selector(startInternal) object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(threadStopped)
name:NSThreadWillExitNotification
object:streamerThread];
[streamerThread start];
MagnatuneAppDelegate *appDelegate = (MagnatuneAppDelegate *)
[[UIApplication sharedApplication] delegate];
appDelegate.playbackThreadFinished = false;
}
... so when the thread stops (or is as close to stopping as I can get
-- I figure if it's about to call exit(), that's good enough), this
happens:
- (void)threadStopped
{
NSLog(@"*** streamer thread has stopped ***");
[[NSNotificationCenter defaultCenter] removeObserver:self];
MagnatuneAppDelegate *appDelegate = (MagnatuneAppDelegate *)
[[UIApplication sharedApplication] delegate];
appDelegate.playbackThreadFinished = true;
}
... and I have this KVO handler:
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSLog(@"observeValueForKeyPath -- current thread ID: %x, keypath:
%s", [NSThread currentThread], [keyPath UTF8String]);
if ([keyPath isEqualToString:@"isPlaying"])
{
.
.
.
}
else if ([keyPath isEqualToString:@"playbackThreadFinished"])
{
if (playbackThreadFinished)
{
// do special stuff that should only happen once the core audio
thread has finished
// nothing UI-related goes on here
[self do_something];
.
.
.
}
[pool release];
return;
}
else if ([keyPath isEqualToString:@"donePlaying"])
{
.
.
.
}
else if ([keyPath isEqualToString:@"nextSong"])
{
.
.
.
}
[pool release];
[super observeValueForKeyPath:keyPath ofObject:object change:change
context:context];
}
So I know the KVO handler gets called on the thread that changed the
value. Are you saying that do_something should happen on the main
thread i.e. performSelectorOnMainThread:@selector(do_something)?
Should I make sure _anything_ that happens in this KVO handler is
dispatched to the main thread in that way?
On Oct 22, 2008, at 2:00 PM, Shawn Erickson wrote:
On Wed, Oct 22, 2008 at 1:46 PM, John Zorko <[EMAIL PROTECTED]> wrote:
Bill,
Alas, I found it 10 minutes after I posted the message *sigh* ... I
forgot
the autorelease pool in my override of
-observeValueForKeyPath:ofObject:change:contet: ... the console
message is
gone now :-)
Humm that has me concerned... it usually isn't a good idea for KVO to
be fired from a secondary thread (since often UI, etc. can be involved
and often that isn't safe to be doing from a secondary thread). You
likely should be bouncing KVO triggering operations to the main
thread.
-Shawn
Regards,
John
Falling You - exploring the beauty of voice and sound
http://www.fallingyou.com
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