UDP LAN networking works in simulation but not iPhone device

Question

gibo772000 OP

Created Apr ’23

Replies 2

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Participants 3

Hi, I am using react-native-udp. It works in the simulation for Xcode iOS16, but not in the actual iPhone device connected to MacBook.

Also I accidentally find out that it works in iOS14 because the iPhone has not been updated to iOS16. But it does not work in iOS16.

I also notice that if I run for the first time it asks networking and I click allow. I added in info the Privacy - Local Network Usage Description and still does not work on actual device.

Notes : Xcode Version 14.3 (14E222b) iOS ver 16.4.1 on iPhone 11 device. MacBook iOS 13.3

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Answer 1

MobileTen OP

Apr ’23

It requires an entitlement from Apple. https://developer.apple.com/documentation/bundleresources/entitlements/com_apple_developer_networking_networkextension https://developer.apple.com/documentation/bundleresources/entitlements/com_apple_developer_networking_multicast

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Answer 2

DTS Engineer OP

Apple

May ’23

There are three common causes of problems like this:

The user has denied your app access to the local network (A).
Your local networking code relies on broadcasts (or multicasts), in which case you need the multicast entitlement (B).
You have a bug in your UDP code (C). Such code is typically based on BSD Sockets and that’s notoriously tricky to use correctly.

I suspect that you’re actually hitting B. Regardless, the Local Network Privacy FAQ covers A and B.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

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