Init NSManagedObject subclass - core-data

Question

I would like to know if it's possible to init a subclass of NSManagedObject ?
I have a class "Actualite" which is a subclass of NSManagedObject and when I want to initialize this class, I get this error :
"CoreData: error: Failed to call designated initializer on NSManagedObject class Actualite", and the app crashes after this message "-[Actualite setTitre:]: unrecognized selector sent to instance 0x8433be0"
Here is my code :
-(void) recupererActualites {
listeNouvellesActualites = [[NSMutableArray alloc] init];
// Convert the supplied URL string into a usable URL object
NSURL *url = [NSURL URLWithString:FACE06_RSS];
// Create a new rssParser object based on the TouchXML "CXMLDocument" class, this is the
// object that actually grabs and processes the RSS data
CXMLDocument *rssParser = [[CXMLDocument alloc] initWithContentsOfURL:url encoding:NSUTF8StringEncoding options:0 error:nil];
// Create a new Array object to be used with the looping of the results from the rssParser
NSArray *resultNodes = NULL;
// Set the resultNodes Array to contain an object for every instance of an node in our RSS feed
resultNodes = [rssParser nodesForXPath:#"//item" error:nil];
NSMutableArray* tmp = [[NSMutableArray alloc] init];
for (CXMLElement* resultElement in resultNodes) {
// Create a temporary MutableDictionary to store the items fields in, which will eventually end up in blogEntries
NSMutableDictionary *blogItem = [[NSMutableDictionary alloc] init];
NSMutableArray* categories = [[NSMutableArray alloc] init];
// Create a counter variable as type "int"
int counter;
// Loop through the children of the current node
for(counter = 0; counter < [resultElement childCount]; counter++) {
// Add each field to the blogItem Dictionary with the node name as key and node value as the value
if([[[resultElement childAtIndex:counter] name] isEqual:#"category"])
[categories addObject:[[resultElement childAtIndex:counter] stringValue]];
else {
if ([[resultElement childAtIndex:counter] stringValue] != nil)
[blogItem setObject:[[resultElement childAtIndex:counter] stringValue] forKey:[[resultElement childAtIndex:counter] name]];
else
[blogItem setObject:#"" forKey:[[resultElement childAtIndex:counter] name]];
}
}
Actualite* actu = [[Actualite alloc] init];
[blogItem setObject:categories forKey:#"categories"];
[actu initWithDictionnary:blogItem];
[tmp addObject:actu];
//[actu release];
[categories release];
[blogItem release];
}
listeNouvellesActualites = tmp;
[rssParser release];
resultNodes = nil;
// Stockage des actualités en local
[self stockerActualites];
}
And the initWithDictionary method set all the attributes of the Actualite class.
I also tried
Actualite* actu = [[Actualite alloc] initWithEntity:[NSEntityDescription entityForName:#"Actualite" inManagedObjectContext:managedObjectContext] insertIntoManagedObjectContext:managedObjectContext];
and
Actualite* actu = (Actualite*)[NSEntityDescription entityForName:#"Actualite" inManagedObjectContext:managedObjectContext];
instead of
Actualite* actu = [[Actualite alloc] init];
The errors disappear but the app stops at this point. I don't know what can I do...
Is someone already had this problem ?
Thanks a lot !

Answer 1

The idea is that you ask for a new object to be created inside a context and then you use it:
Actualite* actu = [NSEntityDescription insertNewObjectForEntityForName:#"Actualite" inManagedObjectContext:managedObjectContext];