If there is a space in the name of a folder within the Engine's install path (eg. Users\Shared\Epic Games\...), the values set in the User Header Search Paths field are split into multiple lines whenever a space occurs in the path. This results in Xcode not being able to perform auto-complete correctly, as well as preventing users from being able to use Jump to Definition to see where something is defined in source code.
SETUP:
Make sure you have a binary version of the Engine installed so that there is a space in the file path (eg: Users\Shared\Epic Games\...).
RESULT:
Any search paths that include a folder that has a space in the name as part of the path are split into two separate paths where the space is located.
EXPECTED:
Each search path is on a single line, regardless of whether a space is included in the name of a folder within the path.
WORKAROUND:
Make sure the Engine is installed so that there are no spaces in the path.
Head over to the existing Questions & Answers thread and let us know what's up.