Coexistence with KVO. Yes, it works!!

[doggy]

KVO works if observers are created after your calls aspect_hookSelector: It most likely will crash the other way around. Still looking for workarounds here - any help appreciated.

Hi, @steipete

I loved aspects, and I really want it can be used by everyone in every projects. But I think the KVO crash is one of limitation which block the way.

So, I have spent many times(and in many ways) to making it works, and hopefully, I got a solution:

• call original selector with the original _cmd

That means we need re-swizzle the originalSelector we saved priviously to class-isa and set invocation.selector with it also before calling [invocation invoke];

All things works like a charm.

KVO Coexistence with different aspects hook mode:

Aspects mode	Hook after KVO	KVO after Hook
Class hook	Works	Works
Instance hook	Works with one limit	Works

All tests above added/updated to the testCase target.

I can provide more detail about why this way has been choosen with this PR if you're interested.

One limitation:

• Instance Hook after KVO

  Doing instance hook on a KVO'ed class will trigger an in-place swizzle, then, the forwardInvocation: will be applied to the isa-swizzled subclass created by KVO. Aspects will works until the isa-swizzled subclass destoryed once all observer has been removed. As our usual practice, removes all observers in dealloc method. This is the same logic as RAC and it's acceptable I think.

Many thanks for all your work on this project!

[doggy]

The version number should be bumped to v1.4.3 I think.

[steipete]

This looks great! Working on a v2 is on my TODO for a while now, the day-to-day work to manage our PDF SDK PSPDFKit takes a lot of work but we also actively use Aspects there so it's not going anywhere. I'll see that I find time on the weekend for that.

Thanks a lot for working on that KVO problem - that's a tough one!

[TozyZuo]

Hi @doggy
I found a new issue about coexistence with KVO.
code like this

id token = [object aspect_hookSelector...]
[object addObserver...] KVO
[token remove]

This will crash.
Because
[className stringByReplacingOccurrencesOfString:AspectsSubclassSuffix withString:@""]
is a Non-existent KVO class.

How could we keep our aspect-hooded class and clean up the object?

[doggy]

@TozyZuo Yeah, you're right!!

Some code for testing the class is needed after trimming aspects' suffix on that class.
I can handle it for several days, I think.

Thanks for the reporting..
Text to me with DingTalk @振坤 if you want.