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Atlas Device SDKs

Work with Realm Files - Swift SDK

On this page

  • Realm Files
  • In-Memory Realms
  • Default Realm
  • Auxiliary Realm Files
  • Find a Realm File Path

A realm is the core data structure used to organize data in Realm. A realm is a collection of the objects that you use in your application, called Realm objects, as well as additional metadata that describe the objects. To learn how to define a Realm object, see Define an Object Model.

Realm stores a binary encoded version of every object and type in a realm in a single .realm file. The file is located at a specific path that you can define when you open the realm. You can open, view, and edit the contents of these files with Realm Studio.

You can also open a realm entirely in memory, which does not create a .realm file or its associated auxiliary files. Instead the SDK stores objects in memory while the realm is open and discards them immediately when all instances are closed.


See: Open an In-Memory Realm

To open an in-memory realm, refer to Open an In-Memory Realm.

Calling Realm() or RLMRealm opens the default realm. This method returns a realm object that maps to a file named default.realm. You can find this file:

  • iOS: in the Documents folder of your app

  • macOS: in the Application Support folder of your app


See: Open a Default Realm

To open a default realm, refer to Open a Default Realm or Realm at a File URL.

Realm creates additional files for each realm:

  • realm files, suffixed with "realm", e.g. default.realm: contain object data.

  • lock files, suffixed with "lock", e.g. default.realm.lock: keep track of which versions of data in a realm are actively in use. This prevents realm from reclaiming storage space that is still used by a client application.

  • note files, suffixed with "note", e.g. default.realm.note: enable inter-thread and inter-process notifications.

  • management files, suffixed with "management", e.g. internal state management.

Deleting these files has important implications. For more information about deleting .realm or auxiliary files, see: Delete a Realm

The realm file is located at a specific path that you can optionally define when you open the realm.

// Get on-disk location of the default Realm
let realm = try! Realm()
print("Realm is located at:", realm.configuration.fileURL!)


See: Open a Realm at a Path

To open a realm at a specific path, refer to Open a Default Realm or Realm at a File URL.

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