# DISPATCH_QUEUE_PRIORITY_BACKGROUND Tasks run at the background priority, which is equivalent to the background quality-of-service level. ``` var DISPATCH_QUEUE_PRIORITY_BACKGROUND: Int32 { get } ``` ## Discussion Use quality-of-service constants instead. This constant maps to the `QOS_CLASS_BACKGROUND` class. Items dispatched to the queue run at background priority; the queue is scheduled for execution after all high priority queues have been scheduled and the system runs items on a thread whose priority is set for background status. Such a thread has the lowest priority and any disk I/O is throttled to minimize the impact on the system. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)