iPhone app crashing when turning device while keyb

Question

I have an iPhone app with a webview that redirects to a forum at some point.

I noticed that the app will crash when I do these steps:

1) Browse through the forum (vBulletin)
2) Open a thread and try to post a message
3) Click into the textarea so the keyboard shows up 4) Then type and/or turn the device quickly

Now my iPhone app crashes. Notice: the crash only appears in very long threads, so it must be some problem of memory or CPU?

Anyway, I can't figure out where to search for the problem, because XCode 4 isn't showing any logs for the crash! Secondly, when running the app via Xcode (on the device) it crashes without showing any error... The crash isn't reproducible via Simulator (of course).

How to solve such a problem?

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CONSOLE:

May 10 00:23:36 unknown SpringBoard[29] <Warning>: Received memory warning. Level=1
May 10 00:23:36 unknown MobilePhone[582] <Warning>: Received memory warning. Level=1
May 10 00:23:37 unknown configd[25] <Notice>: jetsam: kernel memory event (91), free: 1198, active: 7537, inactive: 3482, purgeable: 0, wired: 17615
May 10 00:23:37 unknown SpringBoard[29] <Warning>: Received memory warning. Level=2
May 10 00:23:37 unknown MobilePhone[582] <Warning>: Received memory warning. Level=2
May 10 00:23:38 unknown configd[25] <Notice>: jetsam: kernel termination snapshot being created
May 10 00:23:38 unknown com.apple.launchd[1] <Notice>: (UIKitApplication:com.apple.mobilephone[0xa185]) Exited: Killed: 9
May 10 00:23:38 unknown com.apple.launchd[1] <Notice>: (UIKitApplication:com.skype.skype[0xf18]) Exited: Killed: 9
May 10 00:23:38 unknown com.apple.launchd[1] <Notice>: (UIKitApplication:com.myCompanygmbh.myTestApp[0x9c47]) Bug: launchd_core_logic.c:3795 (24506):0
May 10 00:23:39 unknown com.apple.debugserver-50[598] <Warning>: 1 [0256/1503]: error: ::read ( 4, 0x2ffb19f0, 1024 ) => -1 err = Bad file descriptor (0x00000009)
May 10 00:23:39 unknown SpringBoard[29] <Warning>: Application 'Phone' exited abnormally with signal 9: Killed: 9
May 10 00:23:39 unknown com.apple.launchd[1] <Notice>: (UIKitApplication:com.myCompanygmbh.myTestApp[0x9c47]) Bug: launchd_core_logic.c:3794 (24506):3
May 10 00:23:39 unknown com.apple.launchd[1] <Notice>: (UIKitApplication:com.myCompanygmbh.myTestApp[0x9c47]) Bug: launchd_core_logic.c:3202 (24506):10
May 10 00:23:39 unknown com.apple.launchd[1] <Notice>: (UIKitApplication:com.myCompanygmbh.myTestApp[0x9c47]) Working around 5020256. Assuming the job crashed.
May 10 00:23:39 unknown com.apple.launchd[1] <Warning>: (UIKitApplication:com.myCompanygmbh.myTestApp[0x9c47]) Job appears to have crashed: Segmentation fault: 11
May 10 00:23:39 unknown SpringBoard[29] <Warning>: Application 'Skype' exited abnormally with signal 9: Killed: 9
May 10 00:23:39 unknown SpringBoard[29] <Warning>: Application 'myTestApp' exited abnormally with signal 11: Segmentation fault: 11
May 10 00:23:40 unknown kernel[0] <Debug>: launchd[606] Builtin profile: container (sandbox)
May 10 00:23:40 unknown kernel[0] <Debug>: launchd[606] Container: /private/var/mobile/Applications/1D182D9C-6475-4B81-B409-E6245C60FE84 [69] (sandbox)
May 10 00:23:40 unknown ReportCrash[604] <Error>: Saved crashreport to /Library/Logs/CrashReporter/LowMemory-2011-05-10-002340.plist using uid: 0 gid: 0, synthetic_euid: 0 egid: 0
May 10 00:23:41 unknown Skype[606] <Warning>: ===== Starting HellKit (10021/3.0.0.250/IPHONE) =====
May 10 00:23:41 unknown Skype[606] <Warning>: Running on iOS device model iPhone3,1 (sysctlbyname('hw.machine'))
May 10 00:23:41 unknown Skype[606] <Warning>: Video capture constraints: 12 FPS, complexity mode 8
May 10 00:23:42 unknown MobilePhone[605] <Warning>: UI Mode is Phone
May 10 00:23:43 unknown SpringBoard[29] <Debug>: spd:___libspd_initialize_notify_block_invoke_1:214 spd woke up!
May 10 00:23:43 unknown SpringBoard[29] <Debug>: spd:_libspd_initialize_protocol:142 Registered notification port with spd [PID=609]
May 10 00:23:43 unknown SpringBoard[29] <Debug>: spd:spd_notification_socket_activity:279 Calling session client's callback on their queue for client [PID=606]
May 10 00:23:44 unknown sandboxd[610] <Notice>: Skype(606) deny file-write-create /Applications/.dat025e.000
May 10 00:23:44 unknown mediaserverd[19] <Warning>: 00:23:44.479 <SystemSoundServer> WARNING translating CMSession error: -12985 
May 10 00:23:44 unknown mediaserverd[19] <Warning>: 00:23:44.530 <SystemSoundServer> WARNING translating CMSession error: -12985 
May 10 00:23:44 unknown spd[609] <Error>: spd:spd_vet_socket:658 getpeername failure for client socket [FD=5]: Socket is not connected
May 10 00:23:44 unknown spd[609] <Error>: spd:spd_checkin_socket:954 Unable to check-in unsupported socket for client [PID=606]
May 10 00:23:44 unknown mediaserverd[19] <Error>: 00:23:44.585 <AudioQueueServer> AudioQueue: Error -12985 from AudioSessionSetClientPlayState(606)
May 10 00:23:45 unknown spd[609] <Error>: spd:spd_vet_socket:658 getpeername failure for client socket [FD=6]: Socket is not connected
May 10 00:23:45 unknown spd[609] <Error>: spd:spd_checkin_socket:954 Unable to check-in unsupported socket for client [PID=606]

Answer 1

I've had a similar issue once and here's a possible solution...

First things first, it's very likely to be a memory issue and not the CPU usage, so make sure you implement the - (void)applicationDidReceiveMemoryWarning:(UIApplication *)application delegate method on your app delegate... put a log line there.

Secondly, emulate the low memory warning (simulator has that option in the hardware menu)

Now observe if your app crashes while going from thread to thread (I suspect it will).

If it does crash, then in debugger go through your ivars where it crashes (especially those that correspond to UI components and are loaded from the xib). Make sure they reference what they are supposed to reference: when your app receives a low memory warning, iOS will automatically unload xib resources of hidden views, and if you hold on/depend on any of them somewhere in your code, it's likely that the app will crash if those ivars are not what your code expects.

And the final recommendation: next time you get a crash make sure to include the stack trace. If you don't have the app running in debug mode, you still can get the stack trace by using the "iPhone Configuration Utility" which can read the console output of your device