App will not relaunch after force quit.

[nathanl1192]

I am currently developing an app, which works fine, and I have managed to wipe it of bugs, apart from just one.

When I quit the app through the multitasking bar, and then relaunch it. It freezes and the following line of code is highlighted in green in main.m in xcode 4:

int retVal = UIApplicationMain(argc, argv, nil, nil);

It is followed by the error: Thread 1: Program received signal "SIGKILL".

I have to stop the build, and run it again to get the app to work again.

Does anyone know what the problem is, and how to fix it. This happens when testing on iOS 4.2 and 4.3, running Xcode 4 on Mac OS 10.6.6.

Nathan

[carbonbasednerd]

So, you are running the app on a device and that app is started in xcode. While it's running you force quit the app via the device and then tap the icon on the iphone to open it again?

If you are then i don't think anything is wrong. What's going on is that you are killing the session on the iphone but the session hasn't terminated in xcode and you are trying to open another session on the iphone. Not the most technical explanation - but if that's what you are doing then i don't think there is anything wrong.

[nathanl1192]

Originally Posted by carbonbasednerd

So, you are running the app on a device and that app is started in xcode. While it's running you force quit the app via the device and then tap the icon on the iphone to open it again?

If you are then i don't think anything is wrong. What's going on is that you are killing the session on the iphone but the session hasn't terminated in xcode and you are trying to open another session on the iphone. Not the most technical explanation - but if that's what you are doing then i don't think there is anything wrong.

Thanks for that!

[Skógvur]

I have this problem too, and Xcode is not the problem. Even if I just transfer the compiled application to my device by dragging the files from Finder into the organiser window of Xcode, the same thing happens.

1. Start program. It runs fine.
2. Leave for the home screen by one press on the home button.
3. Double press the home button to access the activity bar, and force quit the app.
4. Try to relaunch the app; the loading image is displayed, but then the program crashes, by SIGKILL, as soon as it hits UIApplicationMain.

EDIT:
Now even this has stopped working; using the run button in Xcode is the only way to get the app up and running on the device again. A new rerun, that is. The same thing will still happen after that, each time. Transferring directly from Finder hasn't been working before either, so maybe I just managed to fool myself in this regard. Anyway, the above thing happens even if I run the program, stop it from Xcode, and then try to run it regardless of Xcode. This does not happen on the iPhone 4 (which does have 4.3.1, though, while the iPad has 4.3.3), but it does happen in both the iPhone 4 simulator and the iPad 2 simulator (4.2 and 4.3, respectively; they're not specified any more than that by Xcode).

EDIT 2:
Hm. It actually does work when dragging from Finder. Random times. Now and then. But it's still the same thing; force quit once, and the program will never boot again until it's reinstalled. SIGKILL.

[Skógvur]

SOLVED:
For some reason, this was solved by changing the deployment target (NameOfProjectInList > Summary > Deployment Target) from 4.3 to 4.3. Extremely weird, but it does most definitely seem to have done the trick. How I close the program isn't very important, either. It just works.

[Billy The Kit]

Originally Posted by carbonbasednerd

So, you are running the app on a device and that app is started in xcode. While it's running you force quit the app via the device and then tap the icon on the iphone to open it again?

If you are then i don't think anything is wrong. What's going on is that you are killing the session on the iphone but the session hasn't terminated in xcode and you are trying to open another session on the iphone. Not the most technical explanation - but if that's what you are doing then i don't think there is anything wrong.

Exactly. But in my case, I was trying to start my app using Safari to trigger the app's Custom URL Scheme. For those readers who might stumble across the same situation as mine, here's the sequence:

- I start the app via Xcode in the simulator.
- I tap the simulator's home button to put my app in background.
- I start Safari and send "myappname://" just to see if it, in fact, brings my app to the foreground. It does.
- Now I want to make sure it kicks off the app while it is terminated, so I double-tap home and kill the app. Important note: Xcode is still running the simulation.
- I return to Safari and send the URL again. The app displays as expected in the simulator but immediately crashes with a SIGKILL error.

I twisted my brain for awhile trying to figure out what was wrong with the code. Turns out, nothing is wrong with the code. To "fix", simply stop the simulation in Xcode as carbonbasednerd explained:

- Stop the Xcode simulation (click "Stop").
- Double-tap the simulator Home button and kill the app again (because it was restarted by Safari even though the app crashed.)
- Return to Safari and send the URL.
- Ta da! The app does a cold start and calls my app delegate's openURL: method, as advertised by Apple.