Hi everyone,
I’m working with UDP Multicasting on iOS (iOS 15+) using Network.framework and facing a confusing issue.
Setup:
Multicast IP: 239.255.0.1
Port: 45454
Using NWConnectionGroup / NWMulticastGroup
NSLocalNetworkUsageDescription is present in Info.plist
Devices are on the same Wi-Fi network
Problem:
Receiving multicast packets works perfectly
Sending multicast packets does NOT work
No errors are thrown
send() completion handler reports success
stateUpdateHandler sometimes doesn’t transition to .ready
No packets are actually transmitted on the network
Observations:
The app can receive data from other multicast senders
Sending appears to be silently blocked
Reinstalling the app fixes the issue
This points to a Local Network permission problem
If permission was denied once, iOS does not re-prompt
Inbound multicast works, outbound multicast is blocked
Questions:
Is it expected on iOS that receiving multicast works even when sending is blocked?
Is reinstalling the app the only way to recover if Local Network permission was denied?
Is there any reliable runtime way to detect that outbound multicast is blocked?
Is NWConnectionGroup the correct and only supported way to send multicast on iOS?
Any clarification or official guidance would really help.
Thanks in advance!
Topic:
Accessibility & Inclusion
SubTopic:
General