Hi everyone, I am building a React Native iOS app that discovers audio devices on the local Wi-Fi network using UDP broadcast + mDNS/Bonjour lookup (similar to the “4Stream” app).
The app works 100% perfectly in Debug mode when installed directly from Xcode. But once I upload it to TestFlight, the local-network features stop working completely:
UDP packets never arrive
Device discovery does not work
Bonjour/mDNS lookup returns nothing
Same phone, same Wi-Fi, same code → only Debug works, TestFlight fails react-native-udp for UDP broadcast
react-native-dns-lookup for resolving hostnames
react-native-xml2js for parsing device responses
In cases like this its important to distinguish the Debug/Release build configuration from Development/Release signing. See Isolating Code Signing Problems from Build Problems. Once you do that, you’re be in a better position to debug this issue.
Also, my experience is that the vast majority of broadcast and multicast problems are caused by folks not using BSD Sockets correctly. See Extra-ordinary Networking > Broadcasts and Multicasts, Hints and Tips.
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