We want to do additional processing (i.e. log the current state) once PLCrashReporter has detected an error (either an exception, signal, etc.) but before the app terminates. Does anyone know if this is possible using PLCrash开发者_高级运维Reporter?

To expand on Andreas' answer --

I've implemented development support in trunk for -[PLCrashReporter setCrashCallbacks:], which permits the execution of a function post-crash, prior to the program exiting.

This wasn't originally included due to the difficulty of implementing async-safe code that can be executed in the context of a crashed process -- it's difficult enough to do that I didn't think anyone would want to do it.

To quote the documentation I wrote for the feature in PLCrashReporter trunk (I don't have a rendered copy posted yet, since the feature has not yet been released):

Async-Safe Programming Guide

Plausible CrashReporter provides support for executing an application specified function in the context of the crash reporter's signal handler, after the crash report has been written to disk. This was a regularly requested feature, and provides the ability to implement application finalization in the event of a crash. However, writing code intended for execution inside of a signal handler is exceptionally difficult, and is not recommended.

Program Flow and Signal Handlers

When the signal handler is called the normal flow of the program is interrupted, and your program is an unknown state. Locks may be held, the heap may be corrupt (or in the process of being updated), and your signal handler may invoke a function that was being executed at the time of the signal. This may result in deadlocks, data corruption, and program termination.

Async-Safe Functions

A subset of functions are defined to be async-safe by the OS, and are safely callable from within a signal handler. If you do implement a custom post-crash handler, it must be async-safe. A table of POSIX-defined async-safe functions and additional information is available from the CERT programming guide - SIG30-C.

Most notably, the Objective-C runtime itself is not async-safe, and Objective-C may not be used within a signal handler.

No, this is not possible. You would have to do your own logging and store that on the filesystem. On the next startup, you could send it alongside the crash report to your server. E.g. using QuincyKit which uses PLCrashReporter and then your own server or HockeyApp.net.

Note: I am the developer of QuincyKit and co-developer of HockeyApp.