My comparison was more with the developer experience. In Smalltalk you live inside your program, doing edits as you go along and with dynamic introspection. In Objective-C you would edit your program from the outside, and then build it after doing changes, maybe introspect it from the outside.

Pharo is a nice implementation of Smalltalk and they have a nice page that describes the top features of the language. Take a look and see if it's different from the developer experience you had with Objective-C: https://archive.is/uAWX5 (linking to a archive via archive.is as some images couldn't load)