You should disable WAL mode in persistentStoreCoordinator method of appDelegate
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();
}