So you're hosting a code review and Xcode is up on the projector (or screen-share via Skype). You look around and notice folks are squinting their eyes (most engineers won't admit their vision is getting worse from coding all those years).
There are a few options to get that font larger and sharper so that even the folks in the back of the room can see what you're talking about when you say "I created a pointer to a pointer of NSError so I can return it from my function as an additional parameter." My favorite option so far: The Xcode Presentation Theme.
To set Presentation Theme, open Xcode Preferences, go to Fonts & Colors, then select Presentation from the Theme list on the left. All appropriate fonts get larger, and the Xcode interface itself stays untouched. Here's a screenshot of the Preference setup:
It's really easy to revert this back to your previous Theme and not mess up your monitor settings, projector settings, or have to use screen zoom that can create blurry text. Now that's Gangnam style.