In the iPad app that I'm creating, I'm trying to handle the uncaught Exceptions by outputting the callStackSymbols of the exception. This can be done with [NSException callStackSymbols]
However, I'd like to be able to see the callStackSymbols on all the other active threads as well. I know I can use [NSThread callStackSymbols] on any thread, but I need to loop through all the active threads to do so.
Is this possible?
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This is a complex area, as Sedate Alien noted. You will need to implement your own stack walking to retrieve a stack trace from the other active threads; APIs such as backtrace(3) and +[NSThread callStackSymbols] will only produce a backtrace for the current thread.
Since I'm familiar with the PLCrashReporter code, I'll just use it for examples:
To fetch the thread list, you'll need to use task_threads(): https://opensource.plausible.coop/stash/projects/PLCR/repos/plcrashreporter/browse/Source/PLCrashLogWriter.m?at=refs%2Ftags%2F1.0#694
Once you have the thread list, you can fetch the thread state via thread_get_state(): https://opensource.plausible.coop/stash/projects/PLCR/repos/plcrashreporter/browse/Source/PLCrashFrameWalker_arm.c?at=refs%2Ftags%2F1.0#73
Using the thread state, you can walk the target's stack: https://opensource.plausible.coop/stash/projects/PLCR/repos/plcrashreporter/browse/Source/PLCrashFrameWalker_arm.c?at=refs%2Ftags%2F1.0#104
Note that all this code is a bit unusual, as it executes within a signal handler and is written to be async-safe; if you're unfamiliar with the complications around signal handling, this is a good starting point: http://www.mikeash.com/pyblog/friday-qa-2011-04-01-signal-handling.html
Implementing this kind of thing correctly is a gigantic headache; I would really recommend that you make use of PLCrashReporter, or one of the products built on top of it (QuincyKit, HockeyApp, Atlassian JMC, etc).
