Child Context new managed object - core-data

Question

I'm trying to use sub context so I can use the subclass of NSManagedObject as a normal class to just hold information. Like a scratch pad...
Target: NSManagedObject
+ (Target*)initWithCoreData{
NSManagedObjectContext * context = [[CoreDataWrapper sharedInstance] childManagedObjectContext];
NSEntityDescription * ent= [NSEntityDescription insertNewObjectForEntityForName:#"Target"
inManagedObjectContext:context];
Target * target = [[Target alloc] initWithEntity:ent insertIntoManagedObjectContext:context];
return target;
}
pragma mark - Core Data
/**
* Path for Core Data Store Files
*
* #return Path for Core Data Store Files
*/
- (NSURL *)applicationDocumentsDirectory {
// The directory the application uses to store the Core Data store file. This code uses a directory named "com.aigptc.MSA" in the application's documents directory.
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
/**
* Create ManagedObjectModel if it doesn't exist already
*
* #return ManagedObjectModel used with CoreData
*/
- (NSManagedObjectModel *)managedObjectModel {
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"MSA" withExtension:#"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
/**
* Return the NSPersistenceStoreCoordinator used in CoreData if it does'nt exist
* with the options: dictionaryWithObjectsAndKeys and NSMigratePersistentStoresAutomaticallyOption set to YES
*
* #return PersistanceStoreCoordinator used by CoreData
*/
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
// The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it.
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
// Create the coordinator and store
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"MSA.sqlite"];
NSError *error = nil;
NSString *failureReason = #"There was an error creating or loading the application's saved data.";
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
[NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
// Report any error we got.
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[NSLocalizedDescriptionKey] = #"Failed to initialize the application's saved data";
dict[NSLocalizedFailureReasonErrorKey] = failureReason;
dict[NSUnderlyingErrorKey] = error;
error = [NSError errorWithDomain:#"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
/**
* Creates NSManagedObjectContext for CoreData
*
* #return NSManagedObjectContext for CoreData
*/
- (NSManagedObjectContext *)managedObjectContext {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (!coordinator) {
return nil;
}
_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
return _managedObjectContext;
}
/**
* Creates NSManagedObjectContext for CoreData
*
* #return NSManagedObjectContext for CoreData
*/
- (NSManagedObjectContext *)childManagedObjectContext {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
if (_childManagedObjectContext != nil) {
return _childManagedObjectContext;
}
_childManagedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
NSManagedObjectContext * cont = [self managedObjectContext];
[_childManagedObjectContext setParentContext:cont];
return _childManagedObjectContext;
}
The program crashes in the line:
Target * target = [[Target alloc] initWithEntity:ent insertIntoManagedObjectContext:context];
with the following error:
2015-08-13 15:52:51.720 MSA[3262:71338] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Target managedObjectModel]: unrecognized selector sent to instance 0x7ffa28e506a0'
*** First throw call stack:
(
0 CoreFoundation 0x000000010c751c65 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x000000010c02ebb7 objc_exception_throw + 45
2 CoreFoundation 0x000000010c7590ad -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
3 CoreFoundation 0x000000010c6af13c ___forwarding___ + 988
4 CoreFoundation 0x000000010c6aecd8 _CF_forwarding_prep_0 + 120
5 CoreData 0x000000010c27fea3 -[NSManagedObject initWithEntity:insertIntoManagedObjectContext:] + 83
6 MSA 0x00000001090db227 +[Target initWithCoreData] + 183
7 MSA 0x00000001090db32a +[Target setTarget:new:targetISO:lastUpdate:] + 154
8 MSA 0x00000001090c53bb -[MSASetTargetView applyTargetButton:] + 651
9 UIKit 0x0000000109bfbd62 -[UIApplication sendAction:to:from:forEvent:] + 75
10 UIKit 0x0000000109d0d50a -[UIControl _sendActionsForEvents:withEvent:] + 467
11 UIKit 0x0000000109d0c499 -[UIControl touchesBegan:withEvent:] + 224
12 UIKit 0x0000000109c487be -[UIWindow _sendTouchesForEvent:] + 325
13 UIKit 0x0000000109c49282 -[UIWindow sendEvent:] + 682
14 UIKit 0x0000000109c0f541 -[UIApplication sendEvent:] + 246
15 UIKit 0x0000000109c1ccdc _UIApplicationHandleEventFromQueueEvent + 18265
16 UIKit 0x0000000109bf759c _UIApplicationHandleEventQueue + 2066
17 CoreFoundation 0x000000010c685431 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
18 CoreFoundation 0x000000010c67b2fd __CFRunLoopDoSources0 + 269
19 CoreFoundation 0x000000010c67a934 __CFRunLoopRun + 868
20 CoreFoundation 0x000000010c67a366 CFRunLoopRunSpecific + 470
21 GraphicsServices 0x000000010f581a3e GSEventRunModal + 161
22 UIKit 0x0000000109bfa8c0 UIApplicationMain + 1282
23 MSA 0x00000001090e798f main + 111
24 libdyld.dylib 0x000000010d6da145 start + 1
25 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
I have no idea what I'm doing wrong... Everything I find on the net is related to the creation of the context in it self.
Many thanks!

Answer 1

I found the answer! I'm creating the Target wrong, it should be:
+ (Target*)initWithCoreData{
NSManagedObjectContext * context = [[CoreDataWrapper sharedInstance] childManagedObjectContext];
Target * target = [NSEntityDescription insertNewObjectForEntityForName:#"Target"
inManagedObjectContext:context];
return target;
}