Special literals in swift are as follows (from [the swift guide]
#file String The name of the file in which it appears.
#line Int The line number on which it appears.
#column Int The column number in which it begins.
#function String The name of the declaration in which it appears.
Prior to Swift 2.2b4, these were
(https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html)):
__FILE__ String The name of the file in which it appears.
__LINE__ Int The line number on which it appears.
__COLUMN__ Int The column number in which it begins.
__FUNCTION__ String The name of the declaration in which it appears.
You can use these in logging statements like so:
println("error occurred on line \(__LINE__) in function \(__FUNCTION__)")