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I just discovered it is possible to force quit a frozen application on iOS. According to the Technical Note TN2151 I should get a crash log on my device with code 0xdeadfa11 but I have no such crashlog.

The exception code 0xdeadfa11 indicated that an application has been force quit by the user. Force quits occur when the user first holds down the On/Off button until "slide to power off" appears, then holds down the Home button. It's reasonable to assume that the user has done this because the application has become unresponsive, but it's not guaranteed - force quit will work on any application.

Note: Terminating a suspended app by removing it from the multitasking tray does not generate a crash report. Once an app has suspended, it is eligible for termination by iOS at any time, so no crash report will be generated.

Is it an apple bug or are there some additional steps I am missing ?

EDIT If I check the device console after the force quit I see this log :

ReportCrash[2074] : Stackshot code 0xdeadfa11 not tasked, ignoring

Seems that for whatever reason iOS decides not to generate deadfall crash report.

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AnderCover
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  • It might be because your app wasn't running at that time when you did force quit. – Akshay Sunderwani Feb 12 '16 at 04:55
  • Actually my app was frozen and I did force quit in order to get a crash report – AnderCover Feb 12 '16 at 15:58
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    hope this might help you http://stackoverflow.com/questions/13907356/ios-how-to-trigger-a-user-force-quit-crash-on-iphone – Akshay Sunderwani Feb 14 '16 at 09:25
  • I will try to generate deadfall with an iOS8 or iOS7 devices, because I did not manage to get the crah report on iOS9 – AnderCover Feb 15 '16 at 09:23
  • Yes, check it, it might be os specific reason that's why it is not generating crash log. – Akshay Sunderwani Feb 15 '16 at 09:26
  • I tried with an iOS8 device and got the same results. Unfortunately I do not have access with an iOS7 device – AnderCover Feb 15 '16 at 09:45
  • Check this out hope it might get you what you requires: https://www.cocoanetics.com/2013/07/taking-stackshots/ – Akshay Sunderwani Feb 15 '16 at 10:33
  • If I am right you are looking out for how to understand reason for frozen app? That why you are trying force quit. If that is the case its better to discuss that as well with some code if possible. As force quit is not necessary to work. – aman.sood Feb 15 '16 at 18:46
  • In fact the bug is already fixed, but I'd like to know why force quit never produces crash report. You say that it is not necessary to work, but do you know what are the conditions to get it working ? If you do, i'll gladly award the bounty to you – AnderCover Feb 16 '16 at 10:31
  • Did you find anything? Also what steps are you following, to generate crash and how are you checking your crash log and did there any other crash log is generating or no log is generated? – Akshay Sunderwani Feb 17 '16 at 11:10
  • No I did not. My steps : open the app I want to force quit, hold down the On/Off button until "slide to power off" appears, then holds down the Home button until Home screen is displayed. Then I go to Xcode > Window > Devices and I select my iPhone No new crash report when I go to View device logs – AnderCover Feb 17 '16 at 11:20
  • In the console I got : SpringBoard[58] : Forcing crash report of (reason: 2, description: power down shortcut) ReportCrash[523] : Stackshot already in progress. SpringBoard[58] : Finished crash reporting. ReportCrash[523] : Stackshot code 0xdeadfa11 not tasked, ignoring com.apple.xpc.launchd[1] (UIKitApplication:com.dxo.DxO-ONE[0xed3a][508]) : Service exited due to signal: Killed: 9 SpringBoard[58] : Application 'UIKitApplication:com.dxo.DxO-ONE[0xed3a]' exited abnormally via signal. – AnderCover Feb 17 '16 at 11:24
  • You are generating crash log at time of debugging via xcode? Am I right? – Akshay Sunderwani Feb 17 '16 at 12:26

2 Answers2

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I tried to generate force quit on three devices:

1)iPad 3 (iOS 8)

2)iPad Air (iOS 9.2)

3)iPhone 5 (iOS 9.2.1)

When I tried to generate crash on all three devices via xcode while debugging, no crash log was generate instead I got the following error message:

Message from debugger: Terminated due to signal 9

which I think similar to your message:

Service exited due to signal: Killed: 9

and when I tried to generate crash without debugging and seeing log via device logs then I found:

1)For iPad 3 (iOS 8): Crash log was generated, screenshot attached.

enter image description here

2)For iPad Air (iOS 9.2): Crash log was not generated.

3)For iPhone 5 (iOS 9.2.1): Crash log was not generated.

As per my understanding, when you try to generate force quit via xcode while debugging, it does not get generated and for case try to generate crash while without debugging directly in your device then it might be os (iOS 9) specific reason.

P.S: And Service exited due to signal: Killed: 9 is generated due to memory issues, and high CPU consumption tasks.

Hope this might help you further.

Akshay Sunderwani
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  • I tried using a generate crash on an iPhone 5C iOS 8.4 using a release build and still no crash and I get the same logs in the console. But whatever ! it's really interesting that you couldn't get any crashlog using an iOS9 device (You definitely earned your bounty :) – AnderCover Feb 17 '16 at 14:54
  • Thanks but I will see further over this different behaviour, as I have taken screenshots for generated crash log and also of device with iOS 9 device where no log was generated. It must be same for all os versions, but I think it is different as it depends on cpu consumption by your application not on every application. – Akshay Sunderwani Feb 17 '16 at 15:09
  • I tried with several app, including some sample app. With and without lightning plugged in. I can't find no deadfa11 crash report on my iOS 8.4 iPhone 5C or within Xcode. I got the impression that the documentation is somehow outdated on this point. it could be a great way to debug app freezes if I could manage to retrieve logs – AnderCover Feb 17 '16 at 15:58
  • I have screenshot of crash log which i got on ios 8 device. – Akshay Sunderwani Feb 18 '16 at 05:49
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The Apple note says that Terminating a suspended app by removing it from the multitasking tray does NOT generate a crash report. I don't think you will have a log.

Ram G.
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  • What the note says is that "Terminating a suspended app by removing it from the multitasking tray does not generate a crash report." And what I did is a force quit – AnderCover Feb 10 '16 at 23:23
  • @AnderCover how do you force quit the application? Is it in code? or double tap the home button and swipe it up? or the stop running button in XCode – Sumeet Feb 17 '16 at 15:03
  • I use the procedure described here : https://developer.apple.com/library/ios/technotes/tn2151/_index.html see my question – AnderCover Feb 17 '16 at 15:48