Accessing from Cycript

Question

I wan't to be able to use associated objects and ISA swizzle, but I can't figure out how to import objc/runtime.h for use with Cycript. I have tried in both the console and in .js files but no luck.

Ideally I'd like to figure out how to include frameworks as well.

You don't need objc/runtime.h for associated objects. And as far as ISA swizzling is concerned, that's one of those things that is highly dangerous in the hands of the unexperienced. And what does console and Javascript have to do with this? — gnasher729, Jul 09 '15 at 23:56

Casey · Accepted Answer · 2015-07-25T20:08:16.870

It seems like a subset of runtime.h is included by default in the Cycript environment. For example, class_copyMethodList and objc_getClass work without any added effort.

var count = new new Type(@encode(int));
var methods = class_copyMethodList(objc_getClass("NSObject"), count);

However objc_setAssociatedObject is not referenced:

objc_getAssociatedObject(someVar, "asdf")
#ReferenceError: Can't find variable: objc_getAssociatedObject

After a lot of searching, I realized the answer was right under my nose. limneos's weak_classdump uses the runtime to do it's dump and Cycript's tutorial shows how to grab C functions.

The solution I ended up with is this:

function setAssociatedObject(someObject, someValue, constVoidPointer) {
    SetAssociatedObject = @encode(void(id, const void*, id, unsigned long))(dlsym(RTLD_DEFAULT, "objc_setAssociatedObject"))
    SetAssociatedObject(someObject, constVoidPointer, someValue, 1)
}

function getAssociatedObject(someObject, constVoidPointer) {
    GetAssociatedObject = @encode(id(id, const void*))(dlsym(RTLD_DEFAULT, "objc_getAssociatedObject"))
    return GetAssociatedObject(someObject, constVoidPointer)
}

It is used like this:

# create void pointer (probably should be a global variable for later retrieval)
voidPtr = new new Type(@encode(const void))

someVar = [[NSObject alloc] init]
setAssociatedObject(someVar, @[@"hello", @"world"], voidPtr)
getAssociatedObject(someVar, voidPtr)
# spits out @["Hello", "World"]

Accessing from Cycript

1 Answers1