How to insert NSManagedObject in other NSManagedObjectContext? - core-data

Question

I am getting data from the server and converts them to an array of NSManagedObject objects.
The array is used to display the table.
How to insert first element array peoples in persistent store?
- (void)viewDidLoad
{
[self loadData];
[self insertFirstPeople];
}
- (NSManagedObjectContext *)managedObjectContext
{
if(!_managedObjectContext) _managedObjectContext = [NSManagedObjectContext MR_context];
return _managedObjectContext;
}
- (void)loadData
{
...
Network Request
...
peoples = [NSMutableArray array];
for (NSDictionary *item in items)
{
People *people = [Podcast MR_createInContext:self.managedObjectContext];
people.name = [item valueForKeyPath:#"im:name.label"];
[peoples addObject:people];
}
}
-(void)insertFirstPeople
{
People *people = peoples[0];
NSManagedObjectContext *moc = [NSManagedObjectContext MR_defaultContext];
[moc insertObject:people]
[moc MR_saveToPersistentStoreAndWait];
}
Error:
An NSManagedObject may only be in (or observed by) a single NSManagedObjectContext.

Answer 1

I myself have found a solution to the problem.
-(void)insertFirstPeople
{
People *people = peoples[0];
CoreDataHelper *helper = [[CoreDataHelper alloc] init];
NSManagerObjectContext *context = [NSManagedObjectContext MR_defaultContext];
[helper saveObject:people toContext:context];
[context MR_saveOnlySelfAndWait];
}
CoreDataHelper.h
#import <Foundation/Foundation.h>
#interface CoreDataHelper : NSObject
{
NSMutableDictionary* _lookup;
}
#property(nonatomic, retain) NSMutableDictionary *lookup;
-(void)saveFrom:(NSManagedObjectContext *)current to:(NSManagedObjectContext *)parent;
- (NSManagedObject *)saveObject:(NSManagedObject *)object toContext:(NSManagedObjectContext *)moc;
- (NSManagedObject*)copyObject:(NSManagedObject*)object
toContext:(NSManagedObjectContext*)moc
parent:(NSString*)parentEntity;
#end
CoreDataHelper.m
#import "CoreDataHelper.h"
#implementation CoreDataHelper
#synthesize lookup = _lookup;
-(void)saveFrom:(NSManagedObjectContext *)current to:(NSManagedObjectContext *)parent
{
NSNotificationCenter *dnc = [NSNotificationCenter defaultCenter];
[dnc addObserverForName:NSManagedObjectContextDidSaveNotification
object:current queue:nil
usingBlock:^(NSNotification *notification)
{
[parent mergeChangesFromContextDidSaveNotification:notification];
}];
NSError *error;
if (![current save:&error])
{
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
}
[dnc removeObserver:self
name:NSManagedObjectContextDidSaveNotification
object:current];
}
- (NSManagedObject *)saveObject:(NSManagedObject *)object toContext:(NSManagedObjectContext *)moc {
NSUndoManager *docUndoMgr = [moc undoManager];
[docUndoMgr beginUndoGrouping];
NSManagedObject *object2 = [self copyObject:object toContext:moc parent:nil];
[moc processPendingChanges];
[docUndoMgr endUndoGrouping];
return object2;
}
- (NSManagedObject *)copyObject:(NSManagedObject *)object
toContext:(NSManagedObjectContext *)moc
parent:(NSString *)parentEntity; {
NSError *error = nil;
NSString *entityName = [[object entity] name];
NSManagedObject *newObject = nil;
if ([moc objectRegisteredForID:object.objectID])
newObject = [moc objectWithID:object.objectID];
else
newObject = [NSEntityDescription
insertNewObjectForEntityForName:entityName
inManagedObjectContext:moc];
if (![moc save:&error])
{
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
}
[[self lookup] setObject:newObject forKey:[object objectID]];
NSArray *attKeys = [[[object entity] attributesByName] allKeys];
NSDictionary *attributes = [object dictionaryWithValuesForKeys:attKeys];
[newObject setValuesForKeysWithDictionary:attributes];
id oldDestObject = nil;
id temp = nil;
NSDictionary *relationships = [[object entity] relationshipsByName];
for (NSString *key in [relationships allKeys]) {
NSRelationshipDescription *desc = [relationships valueForKey:key];
NSString *destEntityName = [[desc destinationEntity] name];
if ([destEntityName isEqualToString:parentEntity]) continue;
if ([desc isToMany]) {
NSMutableSet *newDestSet = [NSMutableSet set];
for (oldDestObject in [object valueForKey:key]) {
temp = [[self lookup] objectForKey:[oldDestObject objectID]];
if (!temp) {
temp = [self copyObject:oldDestObject
toContext:moc
parent:entityName];
}
[newDestSet addObject:temp];
}
[newObject setValue:newDestSet forKey:key];
} else {
oldDestObject = [object valueForKey:key];
if (!oldDestObject) continue;
temp = [[self lookup] objectForKey:[oldDestObject objectID]];
if (!temp && ![destEntityName isEqualToString:parentEntity]) {
temp = [self copyObject:oldDestObject
toContext:moc
parent:entityName];
}
[newObject setValue:temp forKey:key];
}
}
return newObject;
}
#end