# init(qos:flags:block:) Creates a new dispatch work item from an existing block and assigns it the specified quality-of-service class. ``` init(qos: DispatchQoS = .unspecified, flags: DispatchWorkItemFlags = [], block: @escaping () -> Void) ``` ## Parameters `qos` The quality-of-service class to use when prioritizing the work item’s execution. For a list of possible values, see [`DispatchQoS`](/documentation/Dispatch/DispatchQoS). `flags` Configuration flags for the work item. For a list of possible values, see [`DispatchWorkItemFlags`](/documentation/Dispatch/DispatchWorkItemFlags). `block` The block that performs the work. ## Discussion Submit the returned dispatch work item to a queue to schedule it for execution in that queue. Dispatch queues may alter the specified quality-of-service level based on the specified `flags` and the quality-of-service level of the queue’s underlying threads. However, the queue never executes the block with a quality-of-service level lower than the one in the `qos` parameter. You can also execute the dispatch work item directly in the current context by calling its [`perform()`](/documentation/Dispatch/DispatchWorkItem/perform()) method. When performing a work item directly, the system never executes the block with a quality-of-service level lower than the one in the `qos` parameter. --- 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)