Swift sort strings numerically array extension

NumericSortedStringArray.swift

extension Sequence where Iterator.Element == String {
    var sortedByNumberAndString : [String] {
        return self.sorted { (s1, s2) -> Bool in
            return s1.compare(s2, options: .numeric) == .orderedAscending
        }
    }
}

let sorted = ["8 Bob", "7 Joe", "11 Jimmy", "9 Larry", "1 Kyle"].sortedByNumberAndString