调试 iOS 应用程序：在 Xcode 下崩溃但在 iPhone 上继续工作

Question

I am trying to debug my iOS app on iPhone using Xcode.

I'm starting the app through Xcode debugger and application works fine for a couple of minutes. Then i'm getting error message from Xcode:

The app "myapp" on "iPhone_device" quit unexpectedly.
Message from debugger: Terminated due to signal 9

But application on iPhone keeps working like nothing happend.

Is this normal? What is the possible reasons of such Xcode behavior?

UPDATE: my app is VoIP application that working in background. I've just found out that this kind of apps can be started automatically in the background after the crash. Could this be an issue?

Answer 1

Your app is most likely being terminated due to low memory. The best thing is to look at the device console using Xcode's Organizer:

If iOS is running out of memory and killing your app, you should see something like this:

The app "myapp" on "iPhone_device" quit unexpectedly.
Message from debugger: Terminated due to signal 9

You should use the Activity Monitor in Instruments to see how much memory your application is using.

You can also use the Memory Monitor instrument and enable graphing of "Physical Memory Free". If you see the graph approaching 0 before your crash you can be pretty sure it's a memory issue.

Answer 2

This means that your app is using lot of memory and due to this the app is killed. Check for memory leakages.

Answer 3

I got the same error when I was trying to run an app on my iPhone 5s when I had my iPhone 6 connected. All I had to do was disconnect the iPhone 6 and it worked after.

Answer 4

On iOS, an app can seem to keep running. When you put an app in the background, it can be killed by iOS when the device runs out of memory. Unlikely to happen on your Mac with the simulator. If you go back to the app, it will be relaunched and go to the exact place where you left it. User doesn't notice that it was killed in between.