Get all methods of an Objective-C class or instance

Question

In Objective-C I can test whether a given class or instance responds to certain selectors. But how can query a class or instance for all its methods or properties of a class (e.g. a list of all methods or properties)?

Meunier

Answer 1

You'll want to use the Objective C runtime methods, see here: https://developer.apple.com/reference/objectivec/objective_c_runtime

Aletaaletha

This link now redirects to navigation page – Pontormo

Apples docs have gotten more horrible. Buzzy's answer below is a much better answer. – Templet

Answer 2

In addition to Buzzy's answer, for debugging purposes you may use the -[NSObject _methodDescription] private method.

Either in lldb:

(lldb) po [[UIApplication sharedApplication] _methodDescription]

or in code:

@interface NSObject (Private)
- (NSString*)_methodDescription;
@end

// Somewhere in the code:
NSLog(@"%@", [objectToInspect performSelector:@selector(_methodDescription)]);

Output will look as following:

<__NSArrayM: 0x7f9 ddc4359a0>:
in __NSArrayM:
    Class Methods:
        + (BOOL) automaticallyNotifiesObserversForKey:(id)arg1; (0x11503b510)
        + (id) allocWithZone:(_NSZone*)arg1; (0x11503b520)
        + (id) __new:::::(const id*)arg1; (0x114f0d700)
    Instance Methods:
        - (void) removeLastObject; (0x114f669a0)
        - (void) dealloc; (0x114f2a8f0)
        - (void) finalize; (0x11503b2c0)
        - (id) copyWithZone:(_NSZone*)arg1; (0x114f35500)
        - (unsigned long) count; (0x114f0d920)
        - (id) objectAtIndex:(unsigned long)arg1; (0x114f2a730)
        - (void) getObjects:(id*)arg1 range:(_NSRange)arg2; (0x114f35650)
        - (void) addObject:(id)arg1; (0x114f0d8e0)
        - (void) setObject:(id)arg1 atIndex:(unsigned long)arg2; (0x114f99680)
        - (void) insertObject:(id)arg1 atIndex:(unsigned long)arg2; (0x114f0d940)
        - (void) exchangeObjectAtIndex:(unsigned long)arg1 withObjectAtIndex:(unsigned long)arg2; (0x114f8bf80)
        ......
in NSMutableArray:
    Class Methods:
        + (id) copyNonRetainingArray; (0x11ee20178)
        + (id) nonRetainingArray; (0x11ee201e8)
        + (id) nonRetainingArray; (0x120475026)
        + (id) arrayWithCapacity:(unsigned long)arg1; (0x114f74280)
        ......

Chihli

Best answer so far – Stereoscopic

It looks like this method has been renamed to fp_methodDescription (also fp_shortMethodDescription and fp_ivarDescription). – Tweeter

fp_methodDescription lists inherited methods too, up to and including NSObject. fp_shortMethodDescription does not list inherited methods. – Piranha

Answer 3

You can do this and it is extremely well documented at https://developer.apple.com/library/mac/documentation/cocoa/Reference/ObjCRuntimeRef/index.html

To fetch all the instance or class methods of a class, you may use class_copyMethodList and iterate over the results. An example:

 #import <objc/runtime.h>

/**
 *  Gets a list of all methods on a class (or metaclass)
 *  and dumps some properties of each
 *
 *  @param clz the class or metaclass to investigate
 */
void DumpObjcMethods(Class clz) {

    unsigned int methodCount = 0;
    Method *methods = class_copyMethodList(clz, &methodCount);

    printf("Found %d methods on '%s'\n", methodCount, class_getName(clz));

    for (unsigned int i = 0; i < methodCount; i++) {
        Method method = methods[i];

        printf("\t'%s' has method named '%s' of encoding '%s'\n",
               class_getName(clz),
               sel_getName(method_getName(method)),
               method_getTypeEncoding(method));

        /**
         *  Or do whatever you need here...
         */
    }

    free(methods);
}

You will need to make two separate calls to this method. One for the instance methods and another for the class methods:

/**
 *  This will dump all the instance methods
 */
DumpObjcMethods(yourClass);

Calling the same on the metaclass will give you all the class methods

/**
 *  Calling the same on the metaclass gives you
 *  the class methods
 */
DumpObjcMethods(object_getClass(yourClass) /* Metaclass */);

Panama

The import path is hard to find, use: #import <objc/runtime.h> – Dennis

Thanks, may be a typo, "DumpObjcMethods(object_getClass(yourClass) /* Metaclass /);" should be: "DumpObjcMethods(object_getMetaClass(yourClass) / Metaclass */);" – Scrub

@Joey: I don't think there is a typo there. There is no routine called object_getMetaClass. The class objects class is its meta class. – Panama

Answer 4

This is possible via objc_method_list. In order to enumerate your methods, you will have to register all your methods before hand.

The process is straight forward: after you've declared your function you can create an instance of objc_method and register the function name. Then add the objc_method to a objc_method_list and finally pass the objc_method_list to class_addMethods..

Here is a link to get you started: http://theocacao.com/document.page/327

Eurythmic