Local networking connections blocked on Xcode 12 builds

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Created Jul ’21

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We have an ipad that connects to a mac device on the local network. And the connections have suddenly stopped working after Xcode 12 and driving us crazy as to where the issue is. (We don’t have the multicast entitlement capabilities so it wasn’t added to any of our builds. )

Xcode 11: For some reason all our builds from Xcode 11 have successful local network connections on IOS 12 & 14

Xcode 12: but ever since we updated Xcode to 12 local networking on all our builds no longer work on IOS 14. To make it more interesting they do work on older IOS 12 devices.

So we’re left wondering where to apply any solutions here. We’ll apply for multicast but still wondering how it’s possible local networking works only with Xcode 11 builds on all IOS and Xcode 12 builds work only on iOS 12 and not IOS 14

What should we do here? Any tips can help thank you.

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Answer 1

Systems Engineer OP

Apple

Jul ’21

We don’t have the multicast entitlement capabilities so it wasn’t added to any of our builds. Xcode 12: but ever since we updated Xcode to 12 local networking on all our builds no longer work on IOS 14. To make it more interesting they do work on older IOS 12 devices. We’ll apply for multicast but still wondering how it’s possible local networking works only with Xcode 11 builds on all IOS and Xcode 12 builds work only on iOS 12 and not IOS 14

Yes, you need to check your iOS application to see if it is performing multicast functions, specifically interacting with 224.0.0.251. If this is the case, and your app is using sockets, then as of iOS 14.5 you will need to request the Multicast Entitlement and include it in your Entitlements file and in your provisioning profile.

See the information about this here:

Multicast Networking Entitlement Request https://developer.apple.com/contact/request/networking-multicast

What operations require the multicast entitlement? https://developer.apple.com/forums/thread/663875

Using the Multicast Networking Additional Capability https://developer.apple.com/forums/thread/663271

Matt Eaton
DTS Engineering, CoreOS
meaton3@apple.com

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