Why is raising an NSException not bringing down my application?

The Problem

I'm writing a Cocoa application and I want to raise exceptions that will crash the application noisily.

I have the following lines in my application delegate:

[NSException raise:NSInternalInconsistencyException format:@"This should crash the application."];
abort();

The problem is, they don't bring down the application - the message is just logged to the console and the app carries on it's merry way.

As I understand it, the whole point of exceptions is that they're fired under exceptional circumstances. In these circumstances, I want the application to quit in an obvious way. And this doesn't happen.

What I've tried

I've tried:

-(void)applicationDidFinishLaunching:(NSNotification *)note
    // ...
    [self performSelectorOnMainThread:@selector(crash) withObject:nil waitUntilDone:YES];
}

-(void)crash {
    [NSException raise:NSInternalInconsistencyException format:@"This should crash the application."];
    abort();
}

which doesn't work and

-(void)applicationDidFinishLaunching:(NSNotification *)note
    // ...
    [self performSelectorInBackground:@selector(crash) withObject:nil];
}

-(void)crash {
    [NSException raise:NSInternalInconsistencyException format:@"This should crash the application."];
    abort();
}

which, rather confusingly, works as expected.

What's going on? What am I doing wrong?

Edit Report

1 Answer

I'm trying to understand this properly: Why does the following category method on NSApplication lead to an infinite loop? In that infinite loop, "An uncaught exception was raised" is logged out infinitely many times:

- (void)reportException:(NSException *)anException
{
    // handle the exception properly
    (*NSGetUncaughtExceptionHandler())(anException);
}

For testing (and understanding purposes), this is the only thing I do, i.e. just create the above category method. (According to the instructions in http://www.cocoadev.com/index.pl?StackTraces)

Why would this cause an infinite loop? It's not consistent with what the default uncaught exception handler method should do, i.e. just log the exception and exit the program. (See http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/Exceptions/Concepts/UncaughtExceptions.html#//apple_ref/doc/uid/20000056-BAJDDGGD)

Could it be that the default uncaught exception handler is actually throwing the exception again, leading to this infinite loop?

Note: I know it's silly to create only this category method. The purpose of this is to gain a better understanding.

UPDATE: Never mind, I think i get this now. Here is my take. By default, as we know, NSApplication's reportException: method logs the exception. But, according to the docs, the default uncaught exception handler logs the exception and exists the program. However, this should be worded like this in the docs to be more precise: The default uncaught exception handler calls NSApplication's reportException: method (in order to log it, which the method's default implementation indeed does), and then exists the progr

answered 2011-06-02T10:50:00.267

Why is raising an NSException not bringing down my application?

1 Answer

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