I always praised VS debugger, because it allowed move execution pointer back and forth as well as implement some code in intermediate window. I just didn't know, that xcode also allows do that. Moving execution can be done easily by dragging green line (or which color highlighted currently executed line). Actually, this is just nice frontend for
And executing code is possible also in debugger window:
lldb p. Would be nice to have separate window for that, but actually more useful would be to read about other lldb options someday.