# Iterable iOS SDK fails to compile on Xcode 26: ambiguous performAndWait
## What's going on
Compiling an app with Xcode 26 beta 5/6/7 fails with Ambiguous use of 'performAndWait' in the Iterable iOS SDK. The SDK's CoreDataUtils.swift defines an extension on NSManagedObjectContext: a performAndWait generic function taking a throwing closure and returning T, which now collides with the new iOS 26 CoreData method of the same signature. Removing the SDK extension fixes the compile error.
## The verified fix
Fixed upstream: update the Iterable iOS SDK to 6.6.1 or later, where the fix was released. Reporter raid5 confirmed the issue is resolved on the latest master commit and the team closed the issue after the release.
Source: https://github.com/iterable/iterable-swift-sdk/issues/945
## How to use this
Take the question above and check if it matches what you're seeing. If it does, work through the verified fix step by step. Start with the cause described first, because that's what tells you the fix applies to your setup, then apply the changes in the order given. Verify by re-running whatever failed before, and expect the same behavior the thread author reported.