As a software developer, I often need to look into files within the Library folder.
For quick access, I'd like to be able to see the files in my Spotlight searches.
How can I do that?
You can include System Files like those in the Library folders in a Spotlight search, if you use Spotlight within Finder via the search bar in the top right corner of each Finder window.
Just type in your search and click the small + appearing below the search bar. In the opening window search for System files and tick it's box for In Menu and click OK.
Afterwards select System files from the dropdown menu on the left and select are included in the next dropdown.
The process is also described here: How to Search for Hidden, Packaged, and System Files in OS X
If you want a simpler method you can use an alternative for Spotlight like Alfred or LaunchBar. These tools work just like spotlight and can include System files within their search scope besides lots of other features.