Your comments

I see this has been added in build 2056. Thanks!
By the way, in Xcode, the default shortcuts for code completion are Option+Escape to display a list of possible completions and Ctrl+. to instead complete the current word using the first possibility or cycle through them if pressed repeatedly.
Cmd+Space switches the keyboard layout, while Ctrl+Space opens Spotlight. (I just tried to reset my keyboard shortcuts to defaults, and this is still how they are assigned.) Perhaps Cmd+Space is the default for Spotlight if the user only has one keyboard layout set up, but I think this would be strange as it would mean the shortcuts would suddenly change when the user added another keyboard layout. On another note, all single-modifier shortcuts will the space bar are already taken (Cmd switches the keyboard layout, Option inputs a non-breakable space, Ctrl opens Spotlight, Shift… well, that does not quite give a shortcut, as people will expect it to just enter a space), as are Cmd+Option+Space, Option+Ctrl+Space and Ctrl+Shift+Space; it is hard to find a good shortcut for code completion at all.
I have been doing this manually like forever. Of course, it would be really nice to have a single hot key insert all the spaces; however, I believe this would require further knowledge of the syntax of the current file’s programming language than Sublime Text 2 has.