core data database is empty test - objective-c

Question

How can I test if the core data database is empty?
I tried:
NSIndexPath *path1 = [NSIndexPath indexPathForRow:0 inSection:0];
NSManagedObject *managedObject = [self.fetchedResultsController objectAtIndexPath:path1];
if([[managedObject valueForKey:#"date"] description]!=nil){SOMEFUNCTION}else{SOMEFUNCTION}
Thanks

Answer 1

you have to create a fetchrequest for each entity you use in core data. if the fetchrequest returns without results you don't have objects of this entity stored in your core data.
- (BOOL)coreDataHasEntriesForEntityName:(NSString *)entityName {
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:self.managedObjectContext];
[request setEntity:entity];
[request setFetchLimit:1];
NSError *error = nil;
NSArray *results = [self.managedObjectContext executeFetchRequest:request error:&error];
if (!results) {
LogError(#"Fetch error: %#", error);
abort();
}
if ([results count] == 0) {
return NO;
}
return YES;
}

Answer 2

not perfect I admit but it works
my code:
id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:0];
int fufu = [sectionInfo numberOfObjects];
if(fufu!=0){DATABASE IS NOT EMPTY}else{DATABASE IS EMPTY}
if someone know something more efective pls post it

Answer 3

I have these two methods implemented in my appDelegate:
- (NSString *)applicationDocumentsDirectory
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
return basePath;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (persistentStoreCoordinator != nil)
return persistentStoreCoordinator;
NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: #"YourApp.sqlite"]];
NSLog(#"storeURL: %#", storeUrl);
NSError *error;
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: [self managedObjectModel]];
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])
{
/*
Replace this implementation 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. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
Typical reasons for an error here include:
* The persistent store is not accessible
* The schema for the persistent store is incompatible with current managed object model
Check the error message to determine what the actual problem was.
*/
}// if
return persistentStoreCoordinator;
}
The storeUrl prints the path to the sqlite database.
If you open this path with a sqlite manager, you're able to see the content of your sql database. I use this SQLite Manager to analyze sqlite databases: SQLite Manager
(You can only use this method on the simulator)