iOS - Managed object context crashes app when launching from local notification - iphone

Question

I have an app that creates a local notification. When the app is closed (i.e. not running or in the background), it crashes when being launched from the notification. I've managed to figure out which line is crashing the app (stated in a comment below):
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleBlackOpaque];
// Initialise the main view
self.viewController = [[[ViewController alloc] initWithNibName:#"ViewController" bundle:nil] autorelease];
// Initialise a Navigation Controller
UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:self.viewController];
// Set the ViewController as the rootViewController of the window
self.window.rootViewController = nav;
// Colour the navigation bar
nav.navigationBar.tintColor = [UIColor colorWithRed:0.07f green:0.59f blue:0.94f alpha:1];
// Set the background
if (isPhone568) {
self.window.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"santa_back5.png"]];
}
else {
self.window.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"santa_back.png"]];
}
[self.window makeKeyAndVisible];
[nav release];
self.viewController.managedObjectContext = [self managedObjectContext];
application.applicationIconBadgeNumber = 0;
// Handle launching from a notification
UILocalNotification *localNotif = [launchOptions objectForKey:UIApplicationLaunchOptionsLocalNotificationKey];
if (localNotif) {
NSPredicate *predicate = [NSPredicate
predicateWithFormat:#"(dateCreated like %#)",
[localNotif.userInfo objectForKey:#"dateCreated"]];
LetterViewController *letterView = [[LetterViewController alloc] initWithNibName:#"LetterViewController" bundle:nil];
// Get the letter to pass on
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"Letter" inManagedObjectContext:[self managedObjectContext]];
[fetchRequest setEntity:entity];
[fetchRequest setPredicate:predicate];
NSError *error;
//
// THIS NEXT LINE IS CRASHING THE APP
//
NSArray *letters = [[self managedObjectContext] executeFetchRequest:fetchRequest error:&error];
Letter *myLetter = [letters objectAtIndex:0];
letterView.theLetter = myLetter;
//[myLetter release];
// Pass the selected object to the new view controller.
[self.viewController.navigationController pushViewController:letterView animated:YES];
[letterView release];
[fetchRequest release];
}
return YES;
}
I am using the following 3 functions to get the managed object context, persistent store coordinator and managed object model:
//Explicitly write Core Data accessors
- (NSManagedObjectContext *) managedObjectContext {
if (managedObjectContext != nil) {
return managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
managedObjectContext = [[NSManagedObjectContext alloc] init];
[managedObjectContext setPersistentStoreCoordinator: coordinator];
}
return managedObjectContext;
}
- (NSManagedObjectModel *)managedObjectModel {
if (managedObjectModel != nil) {
return managedObjectModel;
}
managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain];
return managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
if (persistentStoreCoordinator != nil) {
return persistentStoreCoordinator;
}
NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory]
stringByAppendingPathComponent: #"<Project Name>.sqlite"]];
NSError *error = nil;
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc]
initWithManagedObjectModel:[self managedObjectModel]];
if(![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil URL:storeUrl options:nil error:&error]) {
/*Error for store creation should be handled in here*/
}
return persistentStoreCoordinator;
}
- (NSString *)applicationDocumentsDirectory {
return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}
Any help in solving this problem would be greatly appreciated.
Thanks in advance.

Answer 1

Couple of things. You appear to be using Core Data on the main thread in what you show, if so all interaction must be on this thread. You should update the code someday to use the new 'perform' API which uses blocks.
Since your localNotif code now does some heavy lifting in the launch delegate it does not return for some time and iOS may kill your app. Take that same code and put it into dispatch block posted to the main queue and it should work. Add some asserts to insure the navigation controller property exists too.

Answer 2

Thanks for the answer. Seems my problem was with the predicate! It doesn't like me using "like" in the where clause. I changed it to an = and it works!