Its always been a little painful when you get an exception and the debugger decides not to cooperate, leaving you with something like:
Thanks!
As far as I could work out, traditional methods of grabbing a symbolic stack trace don’t work on the iPhone. (If I am remembering right, I don’t think NSStackTraceKey exists in UIKit.)
A little while ago I hacked the GTMStackTrace from google-toolbox-for-mac, to lookup the symbolic stack trace from the call stack return addresses (NSException#callStackReturnAddresses introduced in 10.5) and print it out using NSSetUncaughtExceptionHandler. Life has been a little bit easier ever since. Thankfully, the awesome people who work on GTM added it in themselves (see GTMStackTrace.h#61). Here is how you might set it up, in main.m:
#ifdef DEBUG
#import
#import "GTMStackTrace.h"
void exceptionHandler(NSException *exception) {
NSLog(@"%@", GTMStackTraceFromException(exception));
}
#endif
int main(int argc, char *argv[]) {
#ifdef DEBUG
NSLog(@"Debug enabled");
NSDebugEnabled = YES;
NSZombieEnabled = YES;
NSDeallocateZombies = NO;
NSHangOnUncaughtException = YES;
[NSAutoreleasePool enableFreedObjectCheck:YES];
NSSetUncaughtExceptionHandler(&exceptionHandler);
#endif
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
int retVal = UIApplicationMain(argc, argv, nil, nil);
[pool release];
return retVal;
}
For me, DEBUG is set in GCC_PREPROCESSOR_DEFINITIONS via the awesome GTM xcconfg files, which you should also be using. Hopefully, you should get a trace that looks like:
[Session started at 2008-12-30 00:10:13 -0800.] 2008-12-30 00:10:15.772 TestExceptionIPhone[8493:20b] Debug enabled 2008-12-30 00:10:15.830 TestExceptionIPhone[8493:20b] #0 0x92c5614b _NSExceptionSetRubyToken() (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation) #1 0x9657ce3b objc_exception_throw() (/usr/lib/libobjc.A.dylib) #2 0x92c55f2b +[NSException raise:format:arguments:] (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation) #3 0x92c55f6a +[NSException raise:format:] (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation) #4 0x002350 +[TestExceptionIPhoneAppDelegate applicationDidFinishLaunching:] (/Users/gabe/Library/Application Support/iPhone Simulator/User/Applications/586E48B6-B758-4DBD-A534-D6927DA74583/TestExceptionIPhone.app/TestExceptionIPhone) #5 0x30a4e01a +[UIApplication performInitializationWithURL:asPanel:] (/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator2.2.sdk/System/Library/Frameworks/UIKit.framework/UIKit) #6 0x30a57363 +[UIApplication _runWithURL:] (/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator2.2.sdk/System/Library/Frameworks/UIKit.framework/UIKit) #7 0x900425ee +[NSRunLoop runMode:beforeDate:] (/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation) #8 0x92bdcb45 CFRunLoopRunSpecific() (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation) #9 0x92bdccf8 CFRunLoopRunInMode() (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation) #10 0x31564600 GSEventRunModal() (/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator2.2.sdk/System/Library/PrivateFrameworks/GraphicsServices.framework/GraphicsServices) #11 0x315646c5 GSEventRun() (/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator2.2.sdk/System/Library/PrivateFrameworks/GraphicsServices.framework/GraphicsServices) #12 0x30a4ec98 +[UIApplication _run] (/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator2.2.sdk/System/Library/Frameworks/UIKit.framework/UIKit) #13 0x30a5a094 UIApplicationMain() (/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator2.2.sdk/System/Library/Frameworks/UIKit.framework/UIKit) 2008-12-30 00:10:15.834 TestExceptionIPhone[8493:20b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Give me a good stack trace'
And the source of the exception usually starts around the 5th line.
Hi,
This would be great! How can I get GTM set up in my iPhone app (with as small a footprint as possible please).
Thanks
Actually, atos works for the iPhone, at least when you have a debug binary of your app.
For those times when the debugger doesn’t play nice, you can use the cryptic stack trace: take the lower addresses (usually, as in the example above, those that are five or six digits long) that actually correspond to your symbols (as opposed to the system functions that are using much higher addresses), convert to hex and run atos with ‘-arch armv6′ on the debug executable (found in build/Debug-iphoneos).
Oh right on. Yeah I guess I was referring to how you can’t use NSTask in an iphone project, and the advantage of running with the GTMStackTrace stuff is that you can have it automatically dump the trace instead of having to manually run atos after the fact.
Works great. Really.