URL Session Background Task Cancellation Reasons Reasons that indicate why the system canceled a background task. TopicsCancellation reasonsNSURLErrorCancelledReasonBackgroundUpdatesDisabledNSURLErrorCancelledReasonInsufficientSystemResourcesNSURLErrorCancelledReasonUserForceQuitApplication See AlsoKeysNSURLErrorFailingURLErrorKeyNSURLErrorFailingURLPeerTrustErrorKeyNSURLErrorFailingURLStringErrorKeyNSURLErrorBackgroundTaskCancelledReasonKeyNSURLErrorNetworkUnavailableReasonKeyURLError.NetworkUnavailableReason