Xcode comment uncomment issue

You're correct, Xcode is stupid. If you get in this situation, keep hitting cmd-[ to bring the text all the way to the start of the line, then uncomment and it should work. Why Xcode doesn't just remove the first instance of // on a line is beyond me.

Editor->Structure->Uncomment Selection

the option won't show up if lines WITHOUT COMMENTS included into selection

comments must appear AT THE FIRST POSITION to be considered as such