Extension to Count Unique Elements in Array

UniqueElements.swift

extension Array where Element: Comparable {
    var uniqueElements: Int {
        let sorted = self.sorted(by: <)
        let initial: (Element?, Int) = (.none, 0)
        let counter = sorted.reduce(initial) { ($1, $0.0 == $1 ? $0.1 : $0.1 + 1) }
        return counter.1
    }
}