Debugging: do CFZombieLevel and objc_exception_throw() work for you?

FROM : Scott Ellsworth
DATE : Tue Jul 11 21:55:20 2006

Hi, all.

I am putting together a Cocoaheads presentation, and ran into two 
interesting things.

First off, when I use NSZombieEnabled, it acts as expected with non 
bridged objects.  I hit a breakpoint at the point where my code uses 
a zombie:

   NSLog(@"Using zombie object");
   Worker * worker = [[Worker alloc] init];
   [worker release];
   int i = [worker addOne:1];

I tried the same thing with an NSString, and with CFZombieLevel (1, 
19, 5, and a few other values based on the tech note), and all I got 
were bad access exceptions.

   NSString * string = [[NSString alloc] initWithFormat:@"String %d", 12];
   [string release];
   [string length];

Should I have expected this?

Question two:

Setting a breakpoint on -[NSException raise] works great - the 
following code breaks where I expect:

    NSLog(@"Raising exception");
    NSException *badness = [NSException 
exceptionWithName:@"RaisedException"
                                      reason:@"Raised an exception"
                                    userInfo:nil];
    [badness raise];

Setting a breakpoint on objc_exception_throw() does not work with the 
following code.  I end up breaking in [NSException raise] called from 
mouseDown, not in my action method.

   NSLog(@"Throwing exception");
   NSException *badness = [NSException 
exceptionWithName:@"ThrownException"
                                      reason:@"Threw an exception"
                                    userInfo:nil];
   
    @throw badness;

Latest xcode, version 2.3, MacBook Pro, 10.4.7.

Scott


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