How to print the names of all Objective-C classes in an iOS binary?

Question

I want to print the names of all Objective-C classes found in an iOS binary using "otool" or "objdump". I am doing this on macOS, on an iOS binary that is not encrypted.

What I tried:

1. Solution suggested here How to statically dump all ObjC methods called in a Cocoa App?

otool -oV /path to executable/ | grep name | awk '{print $3}'

but i don't know how to only parse the objective-c class names.

2. Solution using "nm" but i dont really like it:

nm /path to executable/ | grep _OBJC_CLASS_

Can you guys help me with a cmd/script to print the names of all Objective-C classes in an iOS binary?

Answer 1

I assume what you don't like about

nm /path to executable/ | grep _OBJC_CLASS_ 

output:

0000000100003d08 S _OBJC_CLASS_$_AppDelegate
                 U _OBJC_CLASS_$_UIResponder
                 U _OBJC_CLASS_$_UIViewController
0000000100003c90 S _OBJC_CLASS_$_ViewController

are the parent classes marked with U.

Using otool I got to:

otool -tv /path to executable/|grep ]|awk '{print substr($1,3)}'|uniq 

yielding in comparison

ViewController
AppDelegate

Answer 2

Here is a little python script that would also do that.

def get_objc_class_names(app_dsym_file):
    # nm app_dsym_file | grep _OBJC_CLASS_  | sed 's/.*$_//g'
    nm = subprocess.Popen(["nm", app_dsym_file], stdout=subprocess.PIPE)
    grep = subprocess.Popen(["grep", "_OBJC_CLASS_"], stdin=nm.stdout, stdout=subprocess.PIPE)

    # Remove leading characters from output like: 000000010a643638 s _OBJC_CLASS_$_MyClass
    sed = subprocess.Popen(["sed", "s/.*$_//g"], stdin=grep.stdout, stdout=subprocess.PIPE)

    nm.stdout.close()  # Allow nm to receive a SIGPIPE if p2 exits.
    grep.stdout.close()  # Allow grep to receive a SIGPIPE if p2 exits.
    output,err = sed.communicate()

    # Get uniq class names
    objc_class_names = set(output.strip().decode('utf8').split('\n'))
    return objc_class_names