#Objective c sqlite database tutorial code#
#Objective c sqlite database tutorial Offline#

You do not, unless you import your existing SQLite database into a Core Data store. How do I use my existing SQLite database with Core Data?

#Objective c sqlite database tutorial code#

You can check the metadata (using metadataForPersistentStoreWithURL:error:) more efficiently than executing a fetch (and it does not require you to hard code any default data values). If there is a possibility that the store (hence file) might be created but the data not imported, you can add a metadata flag to the store. If you are creating a document-based application using NSPersistentDocument, you initialize the defaults in initWithType:error. If it doesn't, you need to import the data. If you are using iOS or creating an application for OS X that is not document-based, you can add a check on application launch to determine whether a file exists at the location you specify for the application’s store. There are also several ways to ensure that the defaults are imported only once:

#Objective c sqlite database tutorial Offline#

It is much better to create a Core Data store yourself offline and use it directly in your application. Parsing a file to create a store incurs unnecessary overhead. When you want to use it, open the file and parse the representation to create managed objects.ĭo not use this technique in iOS, and only if absolutely necessary in OS X. When you want to use it, either copy the whole store to a suitable location, or copy the objects from the defaults store to an existing store.įor small datasets, create the managed objects directly in code.Ĭreate a property list or another file-based representation of the data, and store it as an application resource.

There are several ways to create the data.Ĭreate a separate persistent store that contains the default data and include the store as an application resource. There are two considerations here: creating the data and ensuring the data is imported only once. How do I initialize a store with default data? At the model object level, use a managed object context to perform the fetches directly. Controllers are for managing the interaction between your model objects and your application interface. For example, do not create an instance of NSArra圜ontroller specifically to execute a fetch. It is written for you automatically as part of the template.ĭo not use instances of subclasses of NSController directly to execute fetches. In this case, however, the code to create the context (and the rest of the Core Data stack) is explicit. In a single-window application, if you create your project using the standard project assistant, the application delegate (the instance of the NSApplicationDelegate class) again creates the context and gives you access to it through the managedObjectContext method. In a Cocoa document-based application using NSPersistentDocument, the persistent document typically creates the context and gives you access to it through the managedObjectContext method. Where a managed object context comes from is entirely application-dependent. Frequently Asked Questions Where is a managed object context created?