# unsafeDowncast(_:to:) Returns the given instance cast unconditionally to the specified type. ``` func unsafeDowncast(_ x: AnyObject, to type: T.Type) -> T where T : AnyObject ``` ## Parameters `x` An instance to cast to type `T`. `type` The type `T` to which `x` is cast. ## Return Value The instance `x`, cast to type `T`. ## Discussion The instance passed as `x` must be an instance of type `T`. Use this function instead of `unsafeBitcast(_:to:)` because this function is more restrictive and still performs a check in debug builds. In -O builds, no test is performed to ensure that `x` actually has the dynamic type `T`. > Warning: This function trades safety for performance. Use > `unsafeDowncast(_:to:)` only when you are confident that `x is T` always > evaluates to `true`, and only after `x as! T` has proven to be a > performance problem. --- 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)