NSProxy checking actually work, but throwing those classes that derive from Object class (note I used capitalised O here, the old Object class from early NeXT times, also used heavily in OS X kernel, GCD and Mach ports) into the mix means that no method can be sent before class is determined. I would suggest Apple add one runtime function class_isSubclassOfClass() that mirrors the functionality of NSObject and NSProxy method isSubclassOfClass so that derivatives of the old Object class can be detected more easily.
> On Dec 14, 2014, at 03:49, Gary L. Wade <garyw...@desisoftsystems.com> wrote: > > Are you saying that Apple's well-documented approach to see if an object is > derived from NSProxy does not work? If that's the case, you need to submit a > bug report to Apple. That's a serious issue that only Apple can help you with. > > If you are using objects not derived from NSObject nor NSProxy, then change > your design. > -- > Gary L. Wade (Sent from my iPad) > http://www.garywade.com/ > >> On Dec 13, 2014, at 11:40 AM, Maxthon Chan <m...@maxchan.info> wrote: >> >> Ain’t work! Will crash if an Object derivative showed up. >> >> I am scanning ALL loaded classes and only subclasses of a certain class is >> interested. But due to the nature of this class scanning before I can make >> sure that the class derives from NSObject I cannot call any method on it. >> >>> On Dec 14, 2014, at 03:34, Gary L. Wade <garyw...@desisoftsystems.com> >>> wrote: >>> >>> If all you care about is if an object is a proxy or not, look at isProxy. >>> -- >>> Gary L. Wade (Sent from my iPad) >>> http://www.garywade.com/ >>> >>>> On Dec 13, 2014, at 11:06 AM, Maxthon Chan <m...@maxchan.info> wrote: >>>> >>>> What I am doing here is scanning all loaded classes for subclasses of a >>>> certain class. Before any NSObject method can be issued I have to check if >>>> it is actually NSObject or NSProxy derivative instead of an Object >>>> derivative that does not support NSObject methods. This calls for runtime >>>> equivalent for one of the following NSObject methods: >>>> >>>> - [NSObject respondsToSelector:(SEL)aSelector] = >>>> class_respondsToSelector(Class, SEL) // this crashed. >>>> + [NSObject conformsToProtocol:(Protocol *)aProtocol] = >>>> class_conformsToProtocol(Class, Protocol *) // check for NSObject >>>> protocol, this does not work. >>>> + [NSObject isSubclassOfClass:(Class)aClass] // no equivalent, have to >>>> implement it myself >>>> >>>> I ended up creating this: >>>> >>>> BOOL class_isSubclassOfClass(Class cls, Class other) >>>> { >>>> for (Class c = cls; c; c = class_getSuperclass(c)) >>>> if (c == other) >>>> return YES; >>>> return NO; >>>> } >>>> >>>> If i remembered it right GNUstep runtime have this function. I will file a >>>> bug report to Apple and ask them to add this, as it is useful in class >>>> scanning and i am using this technique heavily in jailbreak detection. >>>> >>>>> On Dec 14, 2014, at 01:20, Kyle Sluder <k...@ksluder.com> wrote: >>>>> >>>>> On Sat, Dec 13, 2014, at 10:19 AM, Phillip Mills wrote: >>>>>> Why do you think the problem is with “respondsToSelector:”? The error >>>>>> says you’re accessing past the end of a string. >>>>> >>>>> Because the crash happens in a call stack that originates in >>>>> class_respondsToSelector, and involves none of Maxthon's code. >>>>> >>>>> --Kyle Sluder >>
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