# UnownedSerialExecutor An unowned reference to a serial executor (a `SerialExecutor` value). ``` @frozen struct UnownedSerialExecutor ``` ## Overview This is an optimized type used internally by the core scheduling operations. It is an unowned reference to avoid unnecessary reference-counting work even when working with actors abstractly. Generally there are extra constraints imposed on core operations in order to allow this. For example, keeping an actor alive must also keep the actor’s associated executor alive; if they are different objects, the executor must be referenced strongly by the actor. ## Topics ### Initializers [`init(Builtin.Executor)`](/documentation/Swift/UnownedSerialExecutor/init(_:)-8mpaa) [`init(E)`](/documentation/Swift/UnownedSerialExecutor/init(_:)-9jcxo) Automatically opt-in to complex equality semantics if the Executor implements `Equatable`. [`init(complexEquality: E)`](/documentation/Swift/UnownedSerialExecutor/init(complexEquality:)) Opts the executor into complex “same exclusive execution context” equality checks. [`init(ordinary: E)`](/documentation/Swift/UnownedSerialExecutor/init(ordinary:)) ### Instance Methods [`func asSerialExecutor() -> (any SerialExecutor)?`](/documentation/Swift/UnownedSerialExecutor/asSerialExecutor()) ## Relationships ### Conforms To [`Sendable`](/documentation/Swift/Sendable) [`Copyable`](/documentation/Swift/Copyable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`BitwiseCopyable`](/documentation/Swift/BitwiseCopyable) --- 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)