Ability to specify a class method as an objection_initializer

[zats]

I implemented ability to have a class method as objection_initializer. Also this pull request contains couple of changes that I would love to hear someone's opinions on.

1. I added an explicit __autoreleasing ARC qualifier for the returning instance since ARC was getting sometimes.
2. objection_initializer's method result is being stored in the returning instance variable. This one was also aimed to fix an edge-case when initialization method wouldn't return the same instance as alloc (which is obviously is not a recommended practice). Also it address all cases when a static factory method is used.

Please let me know if approach I used seems valid to you.

Thank you.

[jdewind]

Good idea.

I'll merge it soon and add tests.

[NachoSoto]

I'm sorry to inform you that this seems to have broken Objection :/

NSMethodSignature *signature = [klass methodSignatureForSelector:initializer];

When using @selector(init) this returns - [NSObject init], as an instance method, but because of how this was implemented it's calling that method on the class instead of the instance.

[zats]

@dewind I just noticed that __autoreleasing qualifier didn't make it through the pull request. Please see the Mantle's code for a good explanation why __autoreleasing is needed in this case. I might be mistaken though, but it seems like a very similar case to me.

[jdewind]

The reason I didn't think it was applicable is that I didn't see the instance being passed via (id *). However, I I just noticed that it does in-fact do that in getReturnValue

For reference (ARC docs):

__autoreleasing to denote arguments that are passed by reference (id *) and are autoreleased

[jdewind]

Fixed in commit 455489f67e36847baca35e25a4524b56ac14d70a