MFMailComposeViewController hangs app on iOS 4.3 - ios

Question

I used the code below to send mail:
MFMailComposeViewController *picker = [[MFMailComposeViewController alloc] init];
picker.mailComposeDelegate = self;
[picker setSubject:#"my title"];
NSMutableString *emailBody = [[NSMutableString alloc] initWithString: #"Hi\n\n"];
[emailBody appendString: #"test"];
[picker setMessageBody:emailBody isHTML:NO];
[self presentModalViewController:picker animated:YES];
[picker release];
[emailBody release];
The code works well on old OS version (Base SDK 5.0, Deployment Target 4.0). I just upgraded to Xcode 4.5 with iOS 6.0 as the Base SDK, Deployment Target still 4.3, and the code still works well on Simulator with 5.0, 5.1, and 6.0.
Now I installed the app to iPad with iOS 4.3.3. The MFMailComposeViewController does not appear, it hogs and the app stops working. I checked the device log, it displays:
Incident Identifier: 53CF815B-36FB-4523-8E58-03D80E6BD2D6
CrashReporter Key: e1ce74069fc4d91cdf244ef60282649f2ea4716e
Hardware Model: iPad1,1
Process: MyApp [1018]
Path: /var/mobile/Applications/75088803-4768-4CD6-A561-553F4A182229/MyApp.app/MyApp
Identifier: MyApp
Version: ??? (???)
Code Type: ARM (Native)
Parent Process: launchd [1]
Date/Time: 2012-11-16 14:29:59.959 +0800
OS Version: iPhone OS 4.3.3 (8J3)
Report Version: 104
Exception Type: 00000020
Exception Codes: 0x8badf00d
Highlighted Thread: 0
Application Specific Information:
MyApp[1018] has active assertions beyond permitted time:
{(
<SBProcessAssertion: 0x1fa0dd00> identifier: Suspending process: MyApp[1018] permittedBackgroundDuration: 10.000000 reason: suspend owner pid:30 preventSuspend preventThrottleDownCPU preventThrottleDownUI
)}
Elapsed total CPU time (seconds): 0.770 (user 0.460, system 0.310), 8% CPU
Elapsed application CPU time (seconds): 0.000, 0% CPU
Thread 0 name: Dispatch queue: com.apple.main-thread
Thread 0:
0 libsystem_kernel.dylib 0x332e5c00 mach_msg_trap + 20
1 libsystem_kernel.dylib 0x332e5758 mach_msg + 44
2 AppSupport 0x33bbb7b8 CPDMTwoWayMessage + 164
3 AppSupport 0x33bba530 -[CPDistributedMessagingCenter _sendMessage:userInfoData:oolKey:oolData:makeServer:receiveReply:nonBlocking:error:] + 352
4 AppSupport 0x33bba0b2 -[CPDistributedMessagingCenter _sendMessage:userInfo:receiveReply:error:toTarget:selector:context:nonBlocking:] + 618
5 AppSupport 0x33bb91ae -[CPDistributedMessagingCenter _sendMessage:userInfo:receiveReply:error:toTarget:selector:context:] + 58
6 AppSupport 0x33bb9312 -[CPDistributedMessagingCenter sendMessageAndReceiveReplyName:userInfo:] + 42
7 MessageUI 0x3693c1fa _CallMessageUIServiceMethod + 182
8 MessageUI 0x3693c01e +[MFMailAccountProxy reloadAccounts] + 22
9 MessageUI 0x3693bf6c +[MFMailComposeController _refreshMailAccountsIfNecessary] + 32
10 MessageUI 0x3693bf2a +[MFMailComposeController isSetupForDelivery] + 10
11 MessageUI 0x3693be80 +[MFMailComposeViewController canSendMail] + 24
12 MessageUI 0x3693bc36 -[MFMailComposeViewController initWithComposition:contentSize:mailComposeControllerOptions:] + 42
13 MessageUI 0x3693bbf8 -[MFMailComposeViewController initWithComposition:] + 28
14 MessageUI 0x36963fac -[MFMailComposeViewController initWithNibName:bundle:] + 44
15 UIKit 0x329e8a0c -[UIViewController init] + 12
16 MyApp 0x000d09ee 0xb5000 + 113134
17 MyApp 0x000e3820 0xb5000 + 190496
18 UIKit 0x32ad1036 -[UIActionSheet(Private) _buttonClicked:] + 186
19 CoreFoundation 0x32dc956a -[NSObject(NSObject) performSelector:withObject:withObject:] + 18
20 UIKit 0x329ceec2 -[UIApplication sendAction:to:from:forEvent:] + 78
21 UIKit 0x329cee62 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 26
22 UIKit 0x329cee34 -[UIControl sendAction:to:forEvent:] + 32
23 UIKit 0x329ceb86 -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 350
24 UIKit 0x329cf41c -[UIControl touchesEnded:withEvent:] + 336
25 UIKit 0x329cdbee -[UIWindow _sendTouchesForEvent:] + 362
26 UIKit 0x329cd568 -[UIWindow sendEvent:] + 256
27 UIKit 0x329b630c -[UIApplication sendEvent:] + 292
28 UIKit 0x329b5c4c _UIApplicationHandleEvent + 5084
29 GraphicsServices 0x35c8ee70 PurpleEventCallback + 660
30 CoreFoundation 0x32e30a90 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 20
31 CoreFoundation 0x32e32838 __CFRunLoopDoSource1 + 160
32 CoreFoundation 0x32e33606 __CFRunLoopRun + 514
33 CoreFoundation 0x32dc3ebc CFRunLoopRunSpecific + 224
34 CoreFoundation 0x32dc3dc4 CFRunLoopRunInMode + 52
35 GraphicsServices 0x35c8e418 GSEventRunModal + 108
36 GraphicsServices 0x35c8e4c4 GSEventRun + 56
37 UIKit 0x329e0d62 -[UIApplication _run] + 398
38 UIKit 0x329de800 UIApplicationMain + 664
39 MyApp 0x000c95a4 0xb5000 + 83364
40 MyApp 0x000b73b8 0xb5000 + 9144
Thread 1 name: Dispatch queue: com.apple.libdispatch-manager
Thread 1:
0 libsystem_kernel.dylib 0x332e8fbc kevent + 24
1 libdispatch.dylib 0x33abc032 _dispatch_mgr_invoke + 706
2 libdispatch.dylib 0x33abd03a _dispatch_queue_invoke + 86
3 libdispatch.dylib 0x33abc5ea _dispatch_worker_thread2 + 186
4 libsystem_c.dylib 0x363d958a _pthread_wqthread + 258
5 libsystem_c.dylib 0x363d9bbc start_wqthread + 0
Thread 2 name: WebThread
Thread 2:
0 libsystem_kernel.dylib 0x332e5c00 mach_msg_trap + 20
1 libsystem_kernel.dylib 0x332e5758 mach_msg + 44
2 CoreFoundation 0x32e312b8 __CFRunLoopServiceMachPort + 88
3 CoreFoundation 0x32e33562 __CFRunLoopRun + 350
4 CoreFoundation 0x32dc3ebc CFRunLoopRunSpecific + 224
5 CoreFoundation 0x32dc3dc4 CFRunLoopRunInMode + 52
6 WebCore 0x31e5c27e RunWebThread(void*) + 382
7 libsystem_c.dylib 0x363d830a _pthread_start + 242
8 libsystem_c.dylib 0x363d9bb4 thread_start + 0
Any comment welcome.

Answer 1

The stack trace looks like this is not your fault, it’s system code that hangs and leads to your app being killed. There’s a post in the Developer Forums (non-public link, sorry) that suggest that this might be connected to the system Mail.app.
I’d try rebooting the device and similar tricks, but in the end your app might still be unstable on 4.3 in general. Do you really need to support 4.3?