What is UICalloutBarButton, and why does it make my app crash?
<p>I'm going through some of the reported crash reports for my iPhone app, and I'm stumped by the following.</p>

<p>It's very possible it crashes somewhere in my code - it may be an event handler calling the wrong selector somewhere.  The problem is I have no idea WHERE this code is - I don't know what a UICalloutBarButton or UICalloutBar is.</p>

<p>Also, needless to say, I can't reproduce this on my end, otherwise it'd be easy to figure out where it's happening.</p>

<pre><code>Date/Time:       2011-03-18 14:33:13.373 +0100
OS Version:      iPhone OS 4.3 (8F190)
Report Version:  104

Exception Type:  EXC_CRASH (SIGABRT)
Exception Codes: 0x00000000, 0x00000000
Crashed Thread:  0

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   libsystem_kernel.dylib          0x317aaa1c __pthread_kill + 8
1   libsystem_c.dylib               0x355593b4 pthread_kill
2   libsystem_c.dylib               0x35551bf8 abort
3   libstdc++.6.dylib               0x33378a64 __gnu_cxx::__verbose_terminate_handler() + 376
4   libobjc.A.dylib                 0x364b506c _objc_terminate
5   libstdc++.6.dylib               0x33376e36 __cxxabiv1::__terminate(void (*)()) + 46
6   libstdc++.6.dylib               0x33376e8a std::terminate() + 10
7   libstdc++.6.dylib               0x33376f5a __cxa_throw + 78
8   libobjc.A.dylib                 0x364b3c84 objc_exception_throw
9   CoreFoundation                  0x354e21b8 -[NSObject(NSObject) doesNotRecognizeSelector:]
10  CoreFoundation                  0x354e1642 ___forwarding___
11  CoreFoundation                  0x35458178 _CF_forwarding_prep_0 + 40
12  CoreFoundation                  0x3544befc -[NSObject(NSObject) performSelector:withObject:]
13  UIKit                           0x35e259b2 -[UICalloutBar buttonPressed:]
14  CoreFoundation                  0x3544befc -[NSObject(NSObject) performSelector:withObject:]
15  UIKit                           0x35e25cd4 -[UICalloutBarButton sendCallback]
16  Foundation                      0x31d096ce __NSFireDelayedPerform
17  CoreFoundation                  0x354b5a40 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__
18  CoreFoundation                  0x354b7ec4 __CFRunLoopDoTimer
19  CoreFoundation                  0x354b883e __CFRunLoopRun
20  CoreFoundation                  0x35448ebc CFRunLoopRunSpecific
21  CoreFoundation                  0x35448dc4 CFRunLoopRunInMode
22  GraphicsServices                0x328e8418 GSEventRunModal
23  GraphicsServices                0x328e84c4 GSEventRun
24  UIKit                           0x35bffd62 -[UIApplication _run]
25  UIKit                           0x35bfd800 UIApplicationMain
26  app name                        0x000022d0 main + 36
27  app name                        0x0000226c start + 44
</code></pre>
