Error message in Core Data - ios

Question

I've been using Core Data in my app, and suddenly I got en error message as follows:
Attempt to add read-only file at path file://localhost/var/mobile/Applications/xxx-xxx-xxx../.app/MyModel.sqlite read/write. Adding it read-only instead. This will be a hard error in the future; you must specify the NSReadOnlyPersistentStoreOption.
The error occurred in the method below:
-(NSPersistentStoreCoordinator*)persistentStoreCoordinator{
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
NSString* path= [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:#"MyModel.sqlite"];
NSURL* storeURL = [[NSURL alloc] initFileURLWithPath:path];
NSError* error = nil;
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
Before today, I have never seen this error message before. Can any one tell me what went wrong? Thank you for your time.

Answer 1

The answer lies in
[[NSBundle mainBundle] resourcePath]
The mainBundle resourcePath is where to load data contained in your application IPA file, it is and will always be readonly, you need to create the sqllite file in the application document folder
you can replace it by
NSURL *storeURL = [[self applicationPrivateDocumentFolderURL] URLByAppendingPathComponent:#"MyModel.sqlite"];
- (NSURL *)applicationPrivateDocumentFolderURL
{
if (!m_privateDocumentFolderURL) {
NSString *applicationPrivateDocumentFolderPath = [[NSFileManager defaultManager] applicationSupportDirectory];
m_privateDocumentFolderURL = [[NSURL alloc] initFileURLWithPath:applicationPrivateDocumentFolderPath];
}
return [[m_privateDocumentFolderURL copy] autorelease];
}

Answer 2

For anyone landing here because they're trying to ship a read-only database with their app, here's the code to create the store
NSDictionary *options = #{NSMigratePersistentStoresAutomaticallyOption: #(true),
NSInferMappingModelAutomaticallyOption: #(true),
NSReadOnlyPersistentStoreOption: #(true))
// The NSReadOnlyPersistentStoreOption is the important one here
NSPersistentStore * seedStore =[coordinator
addPersistentStoreWithType:NSSQLiteStoreType
configuration:#"Seed"
URL:[NSURL fileURLWithPath: [[NSBundle mainBundle] pathForResource:#"Seed" ofType:#".sqlite"]]
options:options
error:&error];
Also, when you create your database, you'll probably have your journal mode set to WAL, which is not compatible with a read-only db. You have 2 choices:
add NSSQLitePragmasOption : #{#"journal_mode" : #"DELETE"}} to your options
or open the seed database with a tool such as Liya and run "PRAGMA wal_checkpoint(RESTART)" followed by "PRAGMA journal_mode = DELETE