a.swift

extension Array {
    func sortedWith<T: Comparable, U: Comparable>(_ comparableTransform: (Array.Element) -> (T, U)) -> [Array.Element] {
        return sorted(by: { (a, b) -> Bool in
            let tupleA = comparableTransform(a)
            let tupleB = comparableTransform(b)
            return tupleA.0 == tupleB.0 && tupleA.1 == tupleB.1
        })
    }
}