Instance Property


A Boolean value that indicates whether the request may use the network when the user has specified Low Data Mode.


var allowsConstrainedNetworkAccess: Bool { get set }


In iOS 13 and later, users can set their device to use Low Data Mode as one of the Cellular Data Options in the Settings app. Users can turn on Low Data Mode to reduce your app’s network data usage. This property controls the request’s behavior when the user turns on Low Data Mode. If there are no nonconstrained network interfaces available and the request’s allowsConstrainedNetworkAccess property is false, any connection created from the request fails. In this case, the error provided when the connection fails has a networkUnavailableReason property whose value is NSURLErrorNetworkUnavailableReason.constrained.

Setting this property on a request overrides the allowsConstrainedNetworkAccess property of URLSessionConfiguration. For example, if the session configuration’s allowsConstrainedNetworkAccess value is false, and you create a task from a request whose allowsConstrainedNetworkAccess is true, the task treats the value as true.

Limit your app’s of use of constrained network access to user-initiated tasks, and put off discretionary tasks until a nonconstrained interface becomes available.

See Also

Supporting Limited Modes

var allowsExpensiveNetworkAccess: Bool

A Boolean value that indicates whether connections may use a network interface that the system considers expensive.