Error on coredata viewcontrollers - objective-c

Question

I have a Core Data stack in which there are two entities: 'Client' and 'Car'. Both are represented by tableViewControllers.
The first tableViewController fetches the list of clients and then once selected, the second displays a list of cars that client owns. Both are pushed onto a navigation controller. When I go 'back' from the second viewcontroller the program shows the firstviewcontroller successfully, waits a second or so then crashes. When I did a 'build and debug' the console gave this error:
Program received signal: “EXC_BAD_ACCESS”.
I dont understand it. Where should I look to find the error?
EDIT:I have included some code below to see if it is due to bad memory handling... I have deleted all commented out methods and as well as those not used before error crops up.
This is my ClientListViewController...
#implementation ClientListViewController
#synthesize clientsArray;
#synthesize coreDataModel;
#pragma mark -
#pragma mark View lifecycle
- (void)viewDidLoad {
[super viewDidLoad];
// Set the title
self.title=#"Clients";
[self populateTable];
}
-(void)populateTable {
[self setClientsArray:[coreDataModel retrieveClientList]];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Override to allow orientations other than the default portrait orientation.
return YES;
}
#pragma mark -
#pragma mark Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
return [clientsArray count];
}
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell...
Client *client = (Client *)[clientsArray objectAtIndex:indexPath.row];
cell.textLabel.text = [client name];
return cell;
[client release];
#pragma mark -
#pragma mark Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
// Create and push new view controller.
ClientCarsViewController *clientCarsViewController = [[ClientCarsViewController alloc] initWithNibName:#"ClientCarsViewController" bundle:nil];
//Pass the CoreDataModel to the view controller
clientCarsViewController.coreDataModel = coreDataModel;
// Pass the selected object to the new view controller
Client *client = (Client *)[clientsArray objectAtIndex:indexPath.row];
clientCarsViewController.client = client;
// Push the new viewController
[self.navigationController pushViewController:clientCarsViewController animated:YES];
// Release the objects
[clientCarsViewController release];
[client release];
}
#pragma mark -
#pragma mark Memory management
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Relinquish ownership any cached data, images, etc. that aren't in use.
}
- (void)viewDidUnload {
// Relinquish ownership of anything that can be recreated in viewDidLoad or on demand.
self.clientsArray = nil;
}
- (void)dealloc {
[clientsArray release];
[coreDataModel release];
[super dealloc];
}
#end
This is my ClientCarsViewController implementation...
#implementation ClientCarsViewController
#synthesize carsArray;
#synthesize coreDataModel;
#synthesize client;
#pragma mark -
#pragma mark View lifecycle
- (void)viewDidLoad {
[super viewDidLoad];
self.title = client.name;
// Get client's cars
NSSet *cars = client.cars;
// Import them into the carsArray
[self setCarsArray: [NSMutableArray arrayWithArray:[cars allObjects]]];
[cars release];
}
-(void)addCarToClient {
[coreDataModel addCarToClient:(Client *)client];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Override to allow orientations other than the default portrait orientation.
return YES;
}
#pragma mark -
#pragma mark Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
return [carsArray count];
}
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell...
Car *car = (Car *)[carsArray objectAtIndex:indexPath.row];
cell.textLabel.text = [car carName];
return cell;
[car release];
}
#pragma mark -
#pragma mark Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
// Navigation logic may go here. Create and push another view controller.
}
#pragma mark -
#pragma mark Memory management
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Relinquish ownership any cached data, images, etc. that aren't in use.
}
- (void)viewDidUnload {
// Relinquish ownership of anything that can be recreated in viewDidLoad or on demand.
self.carsArray = nil;
}
- (void)dealloc {
[self.client release];
[self.coreDataModel release];
[self.carsArray release];
[super dealloc];
}
#end

Answer 1

You are releasing objects you don't own. Have o look at Objective-C Memory Management Rules.
For example, when you obtain an object client like this:
Client *client = (Client *)[clientsArray objectAtIndex:indexPath.row];
You don't own it and should not release it.