App freezes sporadically on Lauch Screen

Hello,


our app is in the App Store since August 18th 2015. It worked very well since then. But in the last couple of weeks, we got negative ratings in the App Store claiming the app is freezing. Moreover, the app seems to slow down the whole device once it froze. We couldn't reproduce the issue until the beginning of the year. Since then we experienced the same bahavior once in a while, while developing further features.


Detailed description:

While deploying the debug version from Xcode to a device, the app sporadically freezes at the launch screen. The debug log shows an appropriate start of the app and doesn't show any errors, exceptions or other suspicious output. What we can see is, that 'applicationDidEnterBackground:' is called before the app freezes. The app doesn't crash and the launch screen is displayed forever. The watchdog deamon doesn't kill the hanging process either. Furthermore the home button doesn't respond to inputs. The device can be recovered by killing the process with Xcode, then we see a black screen. After that, the home button can be pressed twice to remove the app from the recent apps.

Environment:

We experience these issues on iPhone 6 and iPhone 6s Plus with iOS 10.2.1 and 11.2.2 respectively. But we get user reports from various devices and iOS versions. We couldn't reproduce the issue on an iPhone 5 with iOS 9.3.5.

We currently use Xcode 9.2 for development.

Expected bahavior:

We'd expect either a crash with related log entries or the watchdog deamon to kill the hanging application.

I know this is not much info, but I hope anybody can help.

Kind regards

Peter

Replies

First up, I recommend that you try to debug this by launching your app from the Home screen. The debugger launches your app in a non-standard way (so it can debug it, natch), so it’s best to investigate this sort of thing without doing that. Then, once it’s stuck, you can attach with the debugger to see what’s going wrong.

Second, you should grab a sysdiagnose log while the app is hung (for more info on sysdiagnose, see the Bug Reporting > Profiles and Logs page). You may be able to glean something from that but, even if you can’t, the fact the the Home button isn’t working indicates that something is deeply wrong with the system and you should file a bug report about that, making sure to include your sysdiagnose log.

Please post your bug number, just for the record.

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Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

I'm starting to have this problem too with some users of my app.

As in the case of reported by cybergen, users told me that the app remains stuck forever on the launch screen (the main storyboard is never displayed) and the entire operating system becomes difficult to use, as if the app were taking over the entire cpu. Things like displaying control center or go to home become very difficult to perform. The app is never killed by iOS and stay on the launch screen forever.

Unfortunately I cannot debug this situation because I'm unable to reproduce this issue.

cybergen, did you find out what the problem was?

Thank you