核心数据保存异常NSInvalidArgumentException

| 该错误很奇怪，因为它在程序运行时有时会发生。保存上下文大约30次后，程序崩溃。 你能指出我的错误来帮助我吗？谢谢！ -[NSCFNumber UTF8String]：无法识别的选择器已发送到实例0x5a627f0 2011-05-19 17：17：38.650 DMC转到[16892：40b] ***由于未捕获的异常\'NSInvalidArgumentException \'终止了应用程序，原因：\'-[NSCFNumber UTF8String]：无法识别的选择器已发送至实例0x5a627f0 \ ' ***第一次抛出调用堆栈： （     0 CoreFoundation 0x015d95a9 __exceptionPreprocess + 185     1个libobjc.A.dylib 0x0172d313 objc_exception_throw + 44     2 CoreFoundation 0x015db0bb-[NSObject（NSObject）didNotRecognizeSelector：] + 187     3 CoreFoundation 0x0154a966 ___forwarding___ + 966     4 CoreFoundation 0x0154a522 _CF_forwarding_prep_0 + 50     5 CoreData 0x002f970f-[NSSQLiteConnection执行] + 1231     6 CoreData 0x0034bebd-[NSSQLiteConnection updateRow：] + 365     7 CoreData 0x0034ae64-[NSSQLConnection performAdapterOperations：] + 180     8 CoreData 0x0034ab0e-[NSSQLCore _performChangesWithAdapterOps：] + 494     9 CoreData 0x003495ea-[NSSQLCore performChanges] + 410     10 CoreData 0x00343038-[NSSQLCore saveChanges：] + 216     11 CoreData 0x00301199-[NSSQLCore executeRequest：withContext：error：] + 409     12 CoreData 0x003b170b-[NSPersistentStoreCoordinator executeRequest：withContext：error：] + 3691     13 CoreData 0x00339948-[NSManagedObjectContext保存：] + 712     14 DMC转到0x00002f9b-[dmcIpadAppDelegate saveManagedObjectChanges] + 107     15 DMC转到0x00020c25 + [DmcIpadAppDelegate saveManagedObjectChanges] + 117     16 DMC转到0x000276e3-[DownloadFileService watchValueForKeyPath：ofObject：change：context：] + 867     17基础0x00faf1e4 NSKeyValueNotifyObserver + 361     18基础0x00faeca6 NSKeyValueDidChange + 384     19基金会0x00f953e2-[NSObject（NSKeyValueObserverNotification）didChangeValueForKey：] + 123     20 DMC转到0x0002c4d4-[DownloadManager connectionDidFinishLoading：] + 836     21基础0x00fd5112-[NSURLConnection（NSURLConnectionReallyInternal）sendDidFinishLoading] + 108     22基础0x00fd506b _NSURLConnectionDidFinishLoading + 133     23 CFNetwork 0x01dda48e _ZN19URLConnectionClient23_clientDidFinishLoadingEPNS_26ClientConnectionEventQueueE + 220     24 CFNetwork 0x01ea56e1 _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 293     25 CFNetwork 0x01dd0c80 _ZN19URLConnectionClient13processEventsEv + 100     26 CFNetwork 0x01dd0acf _ZN17MultiplexerSource7performEv + 251     27 CoreFoundation 0x015ba8ff __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15     28 CoreFoundation 0x0151888b __CFRunLoopDoSources0 + 571     29 CoreFoundation 0x01517d86 __CFRunLoopRun + 470     30 CoreFoundation 0x01517840 CFRunLoopRunSpecific + 208     31 CoreFoundation 0x01517761 CFRunLoopRunInMode + 97     32个GraphicsServices 0x0202b1c4 GSEventRunModal + 217     33 GraphicsServices 0x0202b289 GSEventRun + 115     34 UIKit 0x00839c93 UIApplicationMain + 1160     35 DMC转到0x00001db9 main + 121     36 DMC转到0x00001d35开始+ 53     37 ??? 0x00000001 0x0 +1 ） 抛出\'NSException \'实例后终止调用 当前语言：自动；目前目标C 杀 放弃