Swift tuples include significant limitations. You cannot programmatically create tuples ("Build me a tuple of length n"). Tuples cannot have mutable length, and there are no variadic tuples (although you can add variadic elements within tuples).
What's more, there's no such thing as a 1-tuple. It's a "nope-le," or, more accurately, a scalar. In Swift, foo and (foo) are identical. In theory, Swift has a labeled 1-tuple; for example, (a:42), but this also currently acts as a simple scalar:
let x = (a:42) x // 42 x == 42 // true x == (42) // true x == (a:42) // true // x.a // error 'Int' does not have a member named 'a'
Swift reflection lets you count the number of fields within a type. The counts returned for these examples are instructive:
var a = (1, 6, 4) var b = (2,3) var c = (2) var d = () reflect(a).count // 3 reflect(b).count // 2 reflect(c).count // 0, scalar, not a tuple, Int 2 reflect(d).count // 0, Void