With Int you may be right.
But there are an infinite number of strings (and indeed every Turing machine may be represented as a String in swift), so it is indeed related to the halting problem.
But there are an infinite number of strings (and indeed every Turing machine may be represented as a String in swift), so it is indeed related to the halting problem.
The article ignores the distinction in many places, but "String" in a Swift function means "the Swift.String type", not "an abstract string type like those used to represent Turing machine state".
And the author clearly acknowledges this:
>it’s best to think of Int as modeling the infinite set of all integers