Re: NSLog every selector on an object?

FROM : Bill Bumgarner
DATE : Sat May 10 19:48:00 2008

> On May 9, 2008, at 9:44 PM, Matt James wrote:

>> Is there any way to overload a class in such a manner as to print 
>> out every
>> method call it makes at any given time before it runs the method? 
>> Right
>> now, I'm overloading a few methods of this particular class and 
>> putting
>> NSLog's at the first line, but I was wondering if there was a way 
>> to jump in
>> before _ALL_ methods on an object and perform this particular task.
>> Thanks for any help!


You could implement an NSProxy type thing and shove that in the 
middle.  Or diddle the isa of the class to point to a new isa that 
logs-and-forwards via various mechanisms described within the previous 
messages (including the link to my weblog, which definitely could be 
hacked to do this).

Personally, I'd use dtrace.  I wrote up a couple of later articles on 
logging / debugging messages to nil.

http://www.friday.com/bbum/2008/01/03/objective-c-using-dtrace-to-trace-messages-to-nil/

http://www.friday.com/bbum/2008/01/26/objective-c-printing-class-name-from-dtrace/

You would want to change the '/arg0==0/' qualifier to qualify for your 
instance of interest.  This will be just a bit non-trivial to do 
compared to the described recipes.  You'll need to stash the id of the 
object of interest into dtrace's world somehow.  You could do so with 
a BEGIN{} hook, but that'll require firing up the dtrace script 
*after* the object has come into existence.  A better solution might 
be to have a couple of dtrace trace points in the script;  one that 
does the qualified logging and one that, when triggered, stashes away 
an object of interest's id such that the qualifier can see it.

b.bum