Connect to an Atlas App Services Backend - Swift SDK

Sync Connection Sharing

You can set the enableSessionMultiplexing bool on the AppConfiguration to specify whether the Realm Swift SDK should open a connection to the server for each synced realm, or share a connection to the server for all synced realms.

If you do not specify a value for this bool, Realm defaults to sharing a single connection per App Services user for all synced realms.

let configuration = AppConfiguration(enableSessionMultiplexing: false)
let app = App(id: YOUR_APP_SERVICES_APP_ID, configuration: configuration)

Sync Timeout Options

You can set various sync timeout options on the AppConfiguration. The syncTimeouts property can accept a SyncTimeoutOptions object to override default values for these settings.

For a complete list of the available timeout settings and their definitions, refer to RLMSyncTimeoutOptions.

let syncTimeoutOptions = SyncTimeoutOptions(
    connectTimeout: 30000,
    connectionLingerTime: 5000,
    pingKeepalivePeriod: 10000,
    pongKeepaliveTimeout: 10000,
    fastReconnectLimit: 30000
)
let configuration = AppConfiguration(syncTimeouts: syncTimeoutOptions)
let app = App(id: YOUR_APP_SERVICES_APP_ID, configuration: configuration)

Connect to a Different Server During Runtime

In some cases, you might want to change the baseURL while the app is running. For example, you might want to roam between Edge Servers, or move from an App Services connection to an Edge Server connection. To change the baseURL during runtime, call the app.updateBaseUrl(to: ) method:

// Specify a baseURL to connect to a server other than the default.
// In this case, an Edge Server instance running on the device.
let configuration = AppConfiguration(baseURL: "http://localhost:80")
let edgeApp = App(id: EDGE_SERVER_APP_ID, configuration: configuration)
// You can check the `baseURL` of an app to define app logic.
if edgeApp.baseURL == "http://localhost:80" {
    print("Client app is currently connected to a local Edge Server instance")
}
// ... log in a user and use the app...
// ... some time later...
try await edgeApp.updateBaseUrl(to: "https://services.cloud.mongodb.com")

This API is experimental, so you must use the experimental import in the file where you want to use this API:

@_spi(RealmSwiftExperimental) import RealmSwift

If you want to change the baseURL after you have logged in a user and have opened a synced database, the app must perform a client reset. Perform these steps in your code:

1. Pause the Sync session.

2. Update the baseURL by calling the app.updateBaseUrl(to: ) method.

3. Authenticate and log the user in again with the new baseURL.

4. Open a synced database pulling data from the new server.

Both the server and the client must be online for the user to authenticate and connect to the new server. If the server is not online or the client does not have a network connection, the user cannot authenticate and open the database.