allowsCellularAccess

allowsCellularAccess is a boolean property of URLSessionConfiguration in Apple’s networking framework. It determines whether a URLSession is allowed to use the device’s cellular data connection for its network requests. When set to true, the session may transmit data over cellular networks; when false, the session will avoid using cellular connectivity and will rely on other available interfaces such as Wi‑Fi.

Default behavior and impact: The default value is true, meaning cellular data is allowed unless explicitly disabled. If a session is configured with allowsCellularAccess set to false, requests initiated by tasks created with that configuration will not start or will fail when only cellular connectivity is available. This setting helps control data usage and roaming costs, or enforce stricter connectivity policies within an app.

Usage: To apply the setting, create or modify a URLSessionConfiguration instance, set allowsCellularAccess, and then create a URLSession with that configuration. For example, a developer might configure a session to avoid cellular data while on a metered network, or during initial app launch to conserve data.

Limitations and scope: The property applies to all tasks created with the given configuration. It does not affect system-level network behavior outside the session's scope. Developers should handle potential errors gracefully for users who lose connectivity on cellular when the setting is disabled.

See also: URLSessionConfiguration, URLSession, network reachability concepts.