Delete a Realm File - Swift SDK

Delete a Realm File to Avoid Migration

If you iterate rapidly as you develop your app, you may want to delete a realm file instead of migrating it when you make schema changes. The Realm configuration provides a deleteRealmIfMigrationNeeded parameter to help with this case.

When you set this property to true, the SDK deletes the realm file when a migration would be required. Then, you can create objects that match the new schema instead of writing migration blocks for development or test data.

do {
    // Delete the realm if a migration would be required, instead of migrating it.
    // While it's useful during development, do not leave this set to `true` in a production app!
    let configuration = Realm.Configuration(deleteRealmIfMigrationNeeded: true)
    let realm = try Realm(configuration: configuration)
} catch {
    print("Error opening realm: \(error.localizedDescription)")
}

Delete a Realm File

In practice, there are two safe times to delete the realm file:

1. On application startup before ever opening the realm.

2. After only having opened the realm within an explicit autorelease pool, which ensures deallocation of all of objects within it.

@autoreleasepool {
    // all Realm usage here -- explicitly guarantee
    // that all realm objects are deallocated
    // before deleting the files
}
// Get configuration
RLMApp *app = [RLMApp appWithId:YOUR_APP_ID];
RLMUser *user = [app currentUser];
RLMRealmConfiguration *configuration = [user configurationWithPartitionValue:@"some partition value"];
configuration.objectClasses = @[Task.class];
NSError *error = nil;
// Delete realm files for that configuration
[RLMRealm deleteFilesForConfiguration:configuration
                                error:&error];
if (error) {
    // Handle error
}

autoreleasepool {
    // all Realm usage here -- explicitly guarantee
    // that all realm objects are deallocated
    // before deleting the files
}
do {
    let app = App(id: APPID)
    let user = try await app.login(credentials: Credentials.anonymous)
    var configuration = user.flexibleSyncConfiguration()
    _ = try Realm.deleteFiles(for: configuration)
} catch {
    // handle error
}

Delete a Realm File During a Client Reset

When you use Device Sync, you may encounter a client reset error. During a client reset, your app must delete the local copy of the realm and download an updated version from the Atlas App Services backend.

Because Synced realms are stored locally and can be used offline, deleting a Synced realm could lose data. If the client has written to the realm and the realm has not uploaded those changes, the client loses that data when you delete the Synced realm. The realm may be unable to upload changes when the client doesn't have a network connection for a long period of time, or in the event of a Sync error that requires you to restart Sync.

For more details on how to handle this scenario, see Client Reset.