核心数据保存例外 [英] Core Data save exception

问题描述

managedObjectContext：save有一个很奇怪的问题。它不是在我第一次保存上下文时发生的，它只是在程序的某个时刻发生的。您能帮我知道为什么会发生，我应该在代码中哪里找到错误？谢谢。

I got very weird issue with managedObjectContext:save. It hasn't happened at the first time I save the context, it only happens at some point of my program. Could you help me to know why it happened and where should I should find a bug in my code? Thanks.

这里是日志：

-[NSCFNumber UTF8String]: unrecognized selector sent to instance 0x5a64110
2011-05-19 16:02:43.235 DMC to Go[98212:40b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFNumber UTF8String]: unrecognized selector sent to instance 0x5a64110'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x015d85a9 __exceptionPreprocess + 185
    1   libobjc.A.dylib                     0x0172c313 objc_exception_throw + 44
    2   CoreFoundation                      0x015da0bb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
    3   CoreFoundation                      0x01549966 ___forwarding___ + 966
    4   CoreFoundation                      0x01549522 _CF_forwarding_prep_0 + 50
    5   CoreData                            0x002f870f -[NSSQLiteConnection execute] + 1231
    6   CoreData                            0x0034aebd -[NSSQLiteConnection updateRow:] + 365
    7   CoreData                            0x00349e64 -[NSSQLConnection performAdapterOperations:] + 180
    8   CoreData                            0x00349b0e -[NSSQLCore _performChangesWithAdapterOps:] + 494
    9   CoreData                            0x003485ea -[NSSQLCore performChanges] + 410
    10  CoreData                            0x00342038 -[NSSQLCore saveChanges:] + 216
    11  CoreData                            0x00300199 -[NSSQLCore executeRequest:withContext:error:] + 409
    12  CoreData                            0x003b070b -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 3691
    13  CoreData                            0x00338948 -[NSManagedObjectContext save:] + 712
    14  DMC to Go                           0x0000313b -[dmcIpadAppDelegate saveManagedObjectChanges] + 107
    15  DMC to Go                           0x00020dc5 +[DmcIpadAppDelegate saveManagedObjectChanges] + 117
    16  DMC to Go                           0x00027883 -[DownloadFileService observeValueForKeyPath:ofObject:change:context:] + 867
    17  Foundation                          0x00fae1e4 NSKeyValueNotifyObserver + 361
    18  Foundation                          0x00fadca6 NSKeyValueDidChange + 384
    19  Foundation                          0x00f943e2 -[NSObject(NSKeyValueObserverNotification) didChangeValueForKey:] + 123
    20  DMC to Go                           0x0002c674 -[DownloadManager connectionDidFinishLoading:] + 836
    21  Foundation                          0x00fd4112 -[NSURLConnection(NSURLConnectionReallyInternal) sendDidFinishLoading] + 108
    22  Foundation                          0x00fd406b _NSURLConnectionDidFinishLoading + 133
    23  CFNetwork                           0x01dd948e _ZN19URLConnectionClient23_clientDidFinishLoadingEPNS_26ClientConnectionEventQueueE + 220
    24  CFNetwork                           0x01ea46e1 _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 293
    25  CFNetwork                           0x01dcfc80 _ZN19URLConnectionClient13processEventsEv + 100
    26  CFNetwork                           0x01dcfacf _ZN17MultiplexerSource7performEv + 251
    27  CoreFoundation                      0x015b98ff __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
    28  CoreFoundation                      0x0151788b __CFRunLoopDoSources0 + 571
    29  CoreFoundation                      0x01516d86 __CFRunLoopRun + 470
    30  CoreFoundation                      0x01516840 CFRunLoopRunSpecific + 208
    31  CoreFoundation                      0x01516761 CFRunLoopRunInMode + 97
    32  GraphicsServices                    0x0202a1c4 GSEventRunModal + 217
    33  GraphicsServices                    0x0202a289 GSEventRun + 115
    34  UIKit                               0x00838c93 UIApplicationMain + 1160
    35  DMC to Go                           0x00001f59 main + 121
    36  DMC to Go                           0x00001ed5 start + 53
    37  ???                                 0x00000001 0x0 + 1
)
terminate called after throwing an instance of 'NSException'

当前语言：自动；当前为Objective-c

Current language: auto; currently objective-c

推荐答案

1. 确保没有警告


2. 将断点放在您认为要在对象上设置 NSString 的代码中


3. 和/或NSLog％@核心数据对象的NSString属性类，并确保它是NSString的某种变体。 （ NSLog（@％@，[obj.property class]）; ）

1. Make sure you have no warnings
2. Put breakpoints in your code where you think you are setting an NSString on your object
3. And/Or NSLog %@ the class of NSString properties of your core data objects and make sure it is some variation of an NSString. (NSLog(@"%@", [obj.property class]);)

发生的事情是您要保存的东西有一个 NSNumber 对象代替了 NSString 。由于 NSNumber 不响应UTF8String，因此您的应用程序崩溃了。

What is happening is something that you are saving has an NSNumber object in place of an NSString. Since NSNumber does not respond to UTF8String your application is crashing.

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