App crashing upon quit

[chuck]

I'm noticing that when my app quits, it shows a black screen instead of smoothly animating out. Then the app icons animate back in like they typically do after a crash. Also, whenever it goes to sleep, it wakes up still working, but no longer accepts user input. Any idea what could be the issue here? I'm wondering if it could be a memory leak or possibly something wrong with the NSTimer. If you have any ideas of how I can fix this, I would be really grateful, because it's my last issue before submitting it to Apple. Thanks!

[Pegolon]

Hi Chuck,
if you are using threads: did you do any GUI centric tasks in a background thread? I had problems with that and called every change to the GUI using [NSObject performSelectorOnMainThread...].

You should really have a look into Instruments! It makes finding trivial memory leaks very easy. Unfortunately finding nontrivial memory leaks is still very difficult.

You might also have a look at this article at CocoaDev about finding autorelease problems.

Hope this helps a little bit.

Cheers,
Markus

[chuck]

I've been working on this all day and haven't had any luck so far. I don't have any background threads, however from the view itself I quite often call

[self setNeedsDisplay];

Perhaps there is a better way to refresh the display? However, I used this in my Random Chess app and had no issues with it. I'm really at a complete loss as to what this issue is. I started using Instruments today, but still don't understand how to use the raw data it throws at me.

I'm reading over the Memory Management documents to dig deeper into object allocation and deallocation to see if I can discover what could be the issue. I'm still open to any other suggestions anyone might have to get me on the right track here.

[xnakx]

anything in the console?
does the app "Program exited with status value:0." upon close/exit?

[chuck]

Here is the complete console output from a session. It does finish with status value: 0. I also notice that when it wakes up the status bar animates in from around 1/5 down the screen back up to the top. It's very strange.

[Session started at 2008-10-03 22:41:08 +0200.]
Loading program into debugger…
GNU gdb 6.3.50-20050815 (Apple version gdb-962) (Mon Aug 11 05:42:45 UTC 2008)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "--host=i386-apple-darwin --target=arm-apple-darwin".tty /dev/ttys000
Program loaded.
target remote-mobile /tmp/.XcodeGDBRemote-16790-25
Switching to remote protocol
mem 0x1000 0x3fffffff cache
mem 0x40000000 0xffffffff none
mem 0x00000000 0x0fff none
sharedlibrary apply-load-rules all
run
Running…
[Switching to thread 10755]
[Switching to thread 10755]
(gdb) continue
warning: UUID mismatch detected with the loaded library - on disk is:
	/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS2.1.sdk/usr/lib/liblockdown.dylib
=uuid-mismatch-with-loaded-file,file="/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS2.1.sdk/usr/lib/liblockdown.dylib"

Debugger stopped.
Program exited with status value:0.

The only thing I'm running thread-wise is NSTimer and I even took that out of the code to see if that could be the issue and it still accepts no input after waking up. I'm getting no hint at all from XCode about what's going on here.

[chuck]

This was an incredibly difficult issue to solve. After a few days of fiddling with it, I finally used one of my two annual code-level incident requests to Apple. They got back to me and said it was a bug in the iPhone OS where a UISlider can't be on a UIToolbar. A workaround was to make the toolbar small at first, put the UISlider next to it and then expand the toolbar so that it covered the slider, thus making it appear like the UISlider belonged on the toolbar. That was that app's last bug, so I submitted it to Apple tonight. Yay!

[PhoneyDeveloper]

Man, they shouldn't charge for an incident if it's the result of a bug in the OS. They should give us credits against incidents if we file bug reports. OTOH, glad they told you the workaround.