Wanted to create a collection of my favorite shortcuts for Xcode. Some of them are muscle memory, but there's many more that I'm not using yet that I wanted to list here, probably more to help me remember than for anything else.

Xcode Navigation

cmd + shift + 2 - open organizer
cmd + option + return - show assistant editor
cmd + return - show standard editor (hide assistant editor)
cmd + shift + o - quickly open or jump to a file
cmd + ctrl + up/down - switch between header and implementation file
cmd + ctrl + left/right - navigate to previous/next file
cmd + click - jump to method declaration
option + click - open quick documentation

Inline

ctrl + spacebar (or escape) - show code completion suggestions
ctrl + a + k + k - delete line
cmd + ctrl + e - rename variable in scope
cmd + f - open find bar
cmd + option + f - open find & replace bar
cmd + e - copy selection to find bar (without copying to clipboard)
cmd + g - find next
cmd + shift + g - find previous
cmd + ] - indent
cmd + [ - outdent
cmd + / - comment/uncomment current line

Also, just stumbled across this great info graphic created by Robert Saunders.