I get the following error:
'NSInvalidArgumentException', reason: 'Illegal attempt to establish a relationship 'condition' between objects in different contexts
when running my iphone app. The relevant part of my model looks like this:
AssessmentTree
-has one TreeCrown
TreeCrown
-has one TreeCrownCondition
-has one AssessmentTree
TreeCrownCondition
-has many TreeCrowns
For the sake of context, I'll mention that this part of the model is designed to allow an arborist to record the condition of a tree's crown. It stores a list of options for assessing the tree crown that can also be edited by the user (So TreeCrownConditions contains the options, and TreeCrown.condition points to the specific selection made in an assessment).
I have a UIPickerView that loads these options and associates the selected option with the AssessmentTree, using the following code in didSelectRow:inComponent:
TreeCrownCondition *fc = (TreeCrownCondition *)[conditionArray objectAtIndex:[conditionPicker selectedRowInComponent:0]];
tree.crown.condition = fc;
When I run this, the first few times I select an option everything is fine, but sometimes (usually after adding/editing/deleting a TreeCrownCondition option) the app will crash on the above lines with the error I posted at the beginning.
The error seems straightforward to fix, except that I'm only using one NSManagedObjectContext throughout the entirety of my app. Each new controller grabs it when it's loaded with the following code:
if(!managedObjectContext){
managedObjectContext = [(AppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
}
I couldn't find very much information about this error or how to resolve it, and I certainly didn't find anyone who'd had this problem without using multiple contexts.
I can only assume I somehow do have multiple contexts, but I can't see how that's possible. What am I missing?
Edit Heres the stack trace:
*** 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'
How are you creating your Entities? If you are creating an entity without a NSManagedObjectContext
it would produce the same error.
From the look of your code I am guessing that what you are getting back out of the picker is not what you are expecting or unnecessarily casting to.
I would put a breakpoint on objc_throw_exception
and duplicate the crash in the debugger. Once you do that then inspect the objects and I expect you will find that what you are getting out of the picker is not a NSManagedObject
but something else.