I've been using Objective-C for about 12 years now. It is similar to Smalltalk in its message system and naming conventions — which, to be fair, were at the core of Kay's Smalltalk vision — but otherwise the experience of programming in Objective-C is not much like programming in Squeak.

That is no bad thing, because programming in Squeak absolutely blows programming in Xcode away.

It's Smalltalk but without the image, without browsers, without inspectors, without live objects, without...

Well... you get it...

If you're interested in seeing what Objective-C would be like with a more Smalltalky environment, you might find F-Script interesting.