UDP Broadcast fails on the first try after the iOS 18.5 update but works after restart

Question

Created 3d

Replies 3

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Upgrade iOS to 18.5, then install app in Xcode and grant permissions to send UDP but it won't work. Then restart device, open this installed app and send UDP again and this time it becomes OK. Repeat these steps and it all goes well. The UDP pod I use in app is CocoaAsyncSocket.

The same thing happens on iPhone 14 Plus and 16 Pro, both iOS 18.5. How to explain this phenomenon, thanks for your help in advance.

Answered by DTS Engineer in 857211022

We made a critical fix to local network privacy in iOS 18.6. For the details, search for FB14321888 in TN3179 Understanding local network privacy.

Given the scope of that bug, it’s hard to say anything conclusive about how local network privacy will behave on iOS 18.x, x < 6. You should focus your testing on 18.6 (and earlier releases, if you support them, and the latest iOS 26 beta).

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

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Answer 1

DTS Engineer OP

Apple

1d

iOS 18.6 has been out for a while. Are you trying to resolve a problem on the older 18.5? Or does this reproduce on iOS 18.6 as well?

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

0

Answer 2

Aibasis OP

12h

@DTS Engineer

Because I just have some iPhones around with OS version 18.5 and test them with Xcode newly compiled app and just happed to see these test results.

And I ran some additional tests on iOS 18.6 and results are as follows.

Xcode compiled or uploaded app has been tested on iOS 18.6.2 and it's ok. But I did not test on older iOS versions or install on older version then upgrade iOS version and test if it would function well.

0

Answer 3

DTS Engineer OP

Apple

5h

Recommended

We made a critical fix to local network privacy in iOS 18.6. For the details, search for FB14321888 in TN3179 Understanding local network privacy.

Given the scope of that bug, it’s hard to say anything conclusive about how local network privacy will behave on iOS 18.x, x < 6. You should focus your testing on 18.6 (and earlier releases, if you support them, and the latest iOS 26 beta).

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

0