# isIsolatingCurrentContext() Checks if the current execution context is isolated by this executor. ``` func isIsolatingCurrentContext() -> Bool? ``` ## Discussion This function can be called by the runtime in order to perform assertions, or attempt to issue warnings about unexpected isolation. This method will be invoked *before* `checkIsolated` and may also be invoked when crashing is not an acceptable outcome of a check (e.g. when attempting to issue isolation *warnings*). Implementations should prefer to implement this method rather than `checkIsolated()` since it can often result in more tailored error messages. It is allowed, and useful for backwards compatibility with old runtimes which are not able to invoke `isIsolatingCurrentContext()` to implement `checkIsolated()`, even if an implementation is able to implement this method. Often times an implementation of `checkIsolated()`, would then invoke `isIsolatingCurrentContext()` and crash if the returned value was `false`. The default implementation returns `nil` is used to indicate that it is “unknown” if the current context is isolated by this serial executor. The runtime then *may* proceed to invoke `checkIsolated()` as a last-resort attempt to verify the isolation of the current context. --- 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)