Ios SecItemUpdate未能及时恢复

在UIApplicationIDBecMeactiveNotification时，我触发一个SecItemUpdate调用：

OSStatus itemError = SecItemUpdate((__bridge CFDictionaryRef)secItemSearchParams, (__bridge CFDictionaryRef)secItemNewData);

我有一个设备（64位+iOS7），它需要大约10秒来评估这一行，并且返回时没有错误（OSStatus=errSecSuccess）

我一直收到一个8badf00d异常（“未能及时恢复”异常，请参阅所附的调用堆栈），因此作为补救措施，我将此逻辑移出了主线程。然而，我不明白为什么SecItemUpdate要花这么多时间来评估！似乎钥匙链或其他资源还没有准备好

有什么线索吗

Call stack:
Exception Type:  00000020
Exception Codes: 0x000000008badf00d
Highlighted Thread:  0

Application Specific Information:
com.MyApp123.MyApp123 failed to resume in time

Elapsed total CPU time (seconds): 3.670 (user 3.670, system 0.000), 15% CPU 
Elapsed application CPU time (seconds): 0.022, 0% CPU

Thread 0:
0   libsystem_kernel.dylib          0x0000000193d49cdc semaphore_wait_trap + 8
1   libxpc.dylib                    0x0000000193e006b0 xpc_connection_send_message_with_reply_sync + 180
2   Security                        0x0000000189f1157c securityd_message_with_reply_sync + 92
3   Security                        0x0000000189f21350 __SecItemUpdate_block_invoke + 300
4   Security                        0x0000000189f20228 SecOSStatusWith + 28
5   Security                        0x0000000189f211e0 SecItemUpdate + 136
6   MyApp123                        0x000000010059472c +[WDKeyChainUtils setKeyChainData:forLabel:] (WDKeyChainUtils.m:39)
7   MyApp123                        0x0000000100173e68 -[DateWatcher setLastSeenDate:] (DateWatcher.m:123)
8   MyApp123                        0x0000000100173ae8 -[DateWatcher watchLogic] (DateWatcher.m:96)
9   MyApp123                        0x0000000100173b68 -[DateWatcher watchOnAppBecomeActiveOrMainKeyDidBecomeAvailable:] (DateWatcher.m:101)
10  CoreFoundation                  0x000000018711f5b0 __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 16
11  CoreFoundation                  0x000000018706c100 _CFXNotificationPost + 2060
12  Foundation                      0x0000000187bfe744 -[NSNotificationCenter postNotificationName:object:userInfo:] + 68
13  UIKit                           0x000000018a1b92e4 -[UIApplication _stopDeactivatingForReason:] + 424
14  UIKit                           0x000000018a36161c -[UIApplication _handleApplicationResumeEvent:] + 1136
15  UIKit                           0x000000018a13532c -[UIApplication handleEvent:withNewEvent:] + 1876
16  UIKit                           0x000000018a134acc -[UIApplication sendEvent:] + 100
17  MyApp123                        0x0000000100266738 -[WDApplication sendEvent:] (WDApplication.m:38)
18  UIKit                           0x000000018a1a1040 _UIApplicationHandleEvent + 668
19  GraphicsServices                0x000000018cd53500 _PurpleEventCallback + 672
20  GraphicsServices                0x000000018cd5302c PurpleEventCallback + 44
21  CoreFoundation                  0x000000018712ae8c __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
22  CoreFoundation                  0x000000018712adec __CFRunLoopDoSource1 + 440
23  CoreFoundation                  0x0000000187129010 __CFRunLoopRun + 1616
24  CoreFoundation                  0x0000000187069c1c CFRunLoopRunSpecific + 448
25  GraphicsServices                0x000000018cd51c08 GSEventRunModal + 164
26  UIKit                           0x000000018a19afd8 UIApplicationMain + 1152
27  MyApp123                        0x0000000100110dc8 main (main.m:17)
28  libdyld.dylib                   0x0000000193c67a9c start + 0