dont you find all the string parsing and manipulation to be quite painful in Swift? I tried to do AoC in Swift before and that put me off a lot. I liked doing little functional one liners but a week from now the parsing burden will be too high.
I program everyday in Swift. I attempted AoC for the first time in Swift last year and gave up after about a week or so for this exact reason and switched to python for the remainder. I don't want to struggle with the awkward string API to do things other languages can do in a line.