我收到以下错误:
'NSInvalidArgumentException',原因:'非法尝试在不同上下文中的对象之间建立关系'条件'
运行我的 iphone 应用程序时。我的模型的相关部分如下所示:
AssessmentTree
-has one TreeCrown
TreeCrown
-has one TreeCrownCondition
-has one AssessmentTree
TreeCrownCondition
-has many TreeCrowns
为了方便起见,我将提到模型的这一部分旨在让树艺师记录树冠的状况。它存储用于评估树冠的选项列表,用户也可以编辑这些选项(因此 TreeCrownConditions 包含选项,TreeCrown.condition 指向评估中所做的特定选择)。
我有一个 UIPickerView 加载这些选项并将所选选项与 AssessmentTree 相关联,使用 didSelectRow:inComponent 中的以下代码:
TreeCrownCondition *fc = (TreeCrownCondition *)[conditionArray objectAtIndex:[conditionPicker selectedRowInComponent:0]];
tree.crown.condition = fc;
当我运行它时,前几次我选择一个选项一切都很好,但有时(通常在添加/编辑/删除 TreeCrownCondition 选项之后)应用程序会在上面的行中崩溃,并出现我在开头发布的错误。
这个错误似乎很容易修复,除了我在整个应用程序中只使用一个 NSManagedObjectContext 。每个新控制器在加载以下代码时都会抓取它:
if(!managedObjectContext){
managedObjectContext = [(AppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
}
我找不到太多关于这个错误或如何解决它的信息,而且我当然没有找到任何人在不使用多个上下文的情况下遇到这个问题。
我只能假设我确实有多个上下文,但我看不出这是怎么可能的。我错过了什么?
编辑继承堆栈跟踪:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Illegal attempt to establish a relationship 'condition' between objects in different contexts (source = <TreeCrown: 0x64b9f00> (entity: TreeCrown; id: 0x648db30 <x-coredata://6E17F271-7670-44EA-9901-5AB58DCA8AC7/TreeCrown/p3> ; data: {
condition = "0x64e5c50 <x-coredata://6E17F271-7670-44EA-9901-5AB58DCA8AC7/TreeCrownCondition/p4>";
images = "<relationship fault: 0x64d5e10 'images'>";
recommendation = "0x64a5320 <x-coredata://6E17F271-7670-44EA-9901-5AB58DCA8AC7/TreeCrownRecommendation/p1>";
tree = "0x6488f70 <x-coredata://6E17F271-7670-44EA-9901-5AB58DCA8AC7/AssessmentTree/p1>";
}) , destination = <TreeCrownCondition: 0xf218a40> (entity: TreeCrownCondition; id: 0xf215c20 <x-coredata://6E17F271-7670-44EA-9901-5AB58DCA8AC7/TreeCrownCondition/p2> ; data: <fault>))'
*** Call stack at first throw:
(
0 CoreFoundation 0x029d5919 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x027ea5de objc_exception_throw + 47
2 CoreData 0x02461810 _PFManagedObject_coerceValueForKeyWithDescription + 1248
3 CoreData 0x02478245 _sharedIMPL_setvfk_core + 197
4 CoreData 0x0247bfe7 _svfk_0 + 39
5 landscapes 0x0000e569 -[AssessmentTreeCRViewController pickerView:didSelectRow:inComponent:] + 571
6 UIKit 0x004647aa -[UIPickerView _sendSelectionChangedForComponent:] + 100
7 UIKit 0x00602ed3 -[UIScroller _scrollAnimationEnded] + 130
8 UIKit 0x0050e792 -[UIAnimator stopAnimation:] + 467
9 UIKit 0x0050e557 -[UIAnimator(Static) _advance:] + 298
10 GraphicsServices 0x034c856d HeartbeatTimerCallback + 35
11 CoreFoundation 0x029b6d43 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 19
12 CoreFoundation 0x029b8384 __CFRunLoopDoTimer + 1364
13 CoreFoundation 0x02914d09 __CFRunLoopRun + 1817
14 CoreFoundation 0x02914280 CFRunLoopRunSpecific + 208
15 CoreFoundation 0x029141a1 CFRunLoopRunInMode + 97
16 GraphicsServices 0x034c52c8 GSEventRunModal + 217
17 GraphicsServices 0x034c538d GSEventRun + 115
18 UIKit 0x0047cb58 UIApplicationMain + 1160
19 landscapes 0x00001eb6 main + 104
20 landscapes 0x00001e45 start + 53
)
terminate called after throwing an instance of 'NSException'