Look at objective-C messages being sent in an application running in the simulator. "Interesting" symbols (configured in the first BEGIN block, or one provided on the command line) will get stack traces dumped. "ignored" symbols are not logged.

spy.d

#!/usr/sbin/dtrace -s

/* Run like:
% sudo csh
# ./spy.d $PROCESS_ID [$INTERESTING_PROBEPROV]

Prints a line of dashes every 5 seconds to delineate different experiments.
*/

#pragma D option quiet
/* don't gripe if $2 (interesting dude) is missing */
#pragma D option defaultargs

BEGIN
{
    /* "Interesting" probemods/funcs cause a stack trace to be dumped when they float by */

    interesting["-viewDidLoad"] = 1;

/* Some other examples:
    interesting["UITouch"] = 1;
    interesting["UITouch(UITouchInternal)"] = 1;
*/
}

BEGIN
{
    /* There is a _lot_ of noise in a typical program.  This is a start on a filter of that stuff. 
     * Add something to ignores to stop any logging about that symbol. */
    ignores["+alloc"] = 1;
    ignores["+allocWithZone:"] = 1;
    ignores["+array"] = 1;
    ignores["+arrayWithObject:"] = 1;
    ignores["+itemType:canBeEnabledForData:style:"] = 1;
    ignores["+self"] = 1;
    ignores["-_copyRenderLayer:layerFlags:commitFlags:"] = 1;
    ignores["-_didCommitLayer:"] = 1;
    ignores["-addObject:"] = 1;
    ignores["-autorelease"] = 1;
    ignores["-bounds"] = 1;
    ignores["-class"] = 1;
    ignores["-contents"] = 1;
    ignores["-copy"] = 1;
    ignores["-copyWithZone:"] = 1;
    ignores["-count"] = 1;
    ignores["-countByEnumeratingWithState:objects:count:"] = 1;
    ignores["-dealloc"] = 1;
    ignores["-frame"] = 1;
    ignores["-hash"] = 1;
    ignores["-init"] = 1;
    ignores["-insertObject:atIndex:"] = 1;
    ignores["-isKindOfClass"] = 1;
    ignores["-layer"] = 1;
    ignores["-length"] = 1;
    ignores["-modelLayer"] = 1;
    ignores["-objectAtIndex:"] = 1;
    ignores["-opacity"] = 1;
    ignores["-rawData"] = 1;
    ignores["-release"] = 1;
    ignores["-replaceObjectAtIndex:withObject:"] = 1;
    ignores["-respondsToSelector:"] = 1;
    ignores["-retain"] = 1;
    ignores["-setItem:enabled:"] = 1;
    ignores["-superlayer"] = 1;
    printf ("Ignoring lots of common stuff\n");
}

objc$1:::entry
/ignores[probefunc] != 1/
{
    printf ("%s %s\n", probemod, probefunc);
}


objc$1:::entry
/probemod == $$2 || probefunc == $$2 || interesting[probemod] == 1 || interesting[probefunc] == 1/
{
    printf ("\nINTERESTING %s %s\n", probemod, probefunc);
    ustack();
}

profile:::tick-5s
{
    printf ("--------------------------------------------------\n");
}

How to use this script, Can it spy message in the iOS device?