Thanks,
Yes, the compiler was complaining about the "*err = *localErr;". I origionally 
had it to be "*err = localErr;" but I was still getting a EXC_BAD_ACCESS error. 
But then the light bulb went off :-)when I read "he isn't checking for nil 
err", and that is exactly what was my problem.

I changed the code a bit per your suggestions. 

return [self getDataForType:aType separator:@"\t" excludeFields:nil error:err];

But the other change I had to make was 

if(err) {
    NSMutableDictionary *errorDetail = [NSMutableDictionary dictionary];
    [errorDetail setValue:@"Failed to find the requested type." 
forKey:NSLocalizedDescriptionKey];
    *err = [NSError errorWithDomain:@"DataForType" code:1 userInfo:errorDetail];
}

return nil;

Thanks for the help,
tom

----- Original Message -----
From: "Ken Thomases" <k...@codeweavers.com>
To: "Tom Jones" <tjo...@acworld.com>
Cc: cocoa-dev@lists.apple.com
Sent: Sunday, October 24, 2010 4:05:19 PM
Subject: Re: NSError help

On Oct 24, 2010, at 5:54 PM, Tom Jones wrote:

> I'm trying to understand why I'm getting thrown in to the debugger when using 
> NSError. I have three methods and I'm overloading them and trying to pass the 
> NSError along the way. What am I doing wrong?

> -(NSString *)getDataForType:(NSString *)aType error:(NSError **)err
> {
>    NSError *localErr = nil;
>    NSString *result = [self getDataForType:aType separator:@"\t" 
> excludeFields:nil error:&localErr];  
>    *err = *localErr;

This is incorrect.  The left and right sides are of two different types.  The 
compiler should have at least warned, if not given an error.

"*localErr" is an NSError.  It's not an NSError* (pointer to NSError), it's 
actually the type of the object (or struct).  There's almost never a case to 
dereference an object pointer like this.

"*err" is an NSError*, a pointer to an NSError.

What you wanted is:

        *err = localErr;

Actually, if you're not doing more with localErr, you can just eliminate it and 
just do:

   NSString *result = [self getDataForType:aType separator:@"\t" 
excludeFields:nil error:err];

The same mistake affects the next method, too.

>    return result;
> }

Regards,
Ken

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