Looking at the Swift standard library, end-exclusive ranges seem to be far more commonly used:
~/build/swift$ git grep -e '\.\.< *[a-zA-Z0-9_(]' --and --not -e '^ *//' -- stdlib/\*.swift | wc -l 599 ~/build/swift$ git grep -e '\.\.\. *[a-zA-Z0-9_(]' --and --not -e '^ *//' -- stdlib/\*.swift | wc -l 112
Looking at the Swift standard library, end-exclusive ranges seem to be far more commonly used: