copying an sqlite file from one project to another - ios

Question

Following this tutorial http://www.raywenderlich.com/12170/core-data-tutorial-how-to-preloadimport-existing-data-updated, I created an empty command line application using core data to seed a database which I subsequently moved (by taking the quizgeodata.sqlite file) over to an ios application I am building. The only other step the tutorial lists for making it work is to add this code to the persistantStoreCoordinator in app delegate
if (![[NSFileManager defaultManager] fileExistsAtPath:[storeURL path]]) {
NSURL *preloadURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:#"quizgeodata" ofType:#"sqlite"]];
NSError* err = nil;
if (![[NSFileManager defaultManager] copyItemAtURL:preloadURL toURL:storeURL error:&err]) {
NSLog(#"Oops, could copy preloaded data");
}
}
(Previous steps included taking the class files (that correspond to the entities) and the ...xcdatamodel.d file into the empty command line application to make sure that the schemas would be the same). When I run the code in the empty command line application, it shows the fetched data that I imported in the log statements, so I assume by copying the quizgeodata.sqlite back to the ios application and adding that one bit of code in the persistent store coordinator, then the following code (in viewDidLoad) should fetch the data from core data, but the log statements are showing that no data's been retrieved. The log of the error in the code below says 'null' (meaning no error I assume) and when I ask xCode to print the sql statements it shows this in the console
2014-04-17 16:11:57.477 qbgeo[767:a0b] CoreData: annotation: total fetch execution time: 0.0026s for 0 rows.
so obviously there's no data in the sqlite file that I copied over. Can you explain what I might need to do to get it working?
Please note that I ran Project > Clean several times so that is not the issue
from ViewDidLoad
id delegate = [[UIApplication sharedApplication] delegate];
self.managedObjectContext = [delegate managedObjectContext];
NSError *error;
if (![self.managedObjectContext save:&error]) {
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"Sportsquiz" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
NSLog(#"error %#", [error description]);
NSArray *messedUpObjects = [managedObjectContext executeFetchRequest:fetchRequest error:&error];
for (Sportsquiz *info in messedUpObjects) {
NSLog(#"correctAnswer %#", [info valueForKey:#"question"]);
NSLog(#"correctAnswer %#", [info valueForKey:#"correctAnswer"]);
}

Answer 1

Let's try:
The original project:
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"TinMung.sqlite"];
NSError *error = nil;
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSMutableDictionary *pragmaOptions = [NSMutableDictionary dictionary];
/*ATTETION: disable WAL mode*/
[pragmaOptions setObject:#"DELETE" forKey:#"journal_mode"];
NSNumber *optionYes = [NSNumber numberWithBool:YES];
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
[NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption,
pragmaOptions, NSSQLitePragmasOption,
optionYes,NSMigratePersistentStoresAutomaticallyOption ,nil];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
abort();
}
return _persistentStoreCoordinator;
}
Copy sqlite file to new project and fetch. I think it will work.