Extending Array to check if it is sorted in Swift?

Question

I want to extend Array class so that it can know whether it is sorted (ascending) or not. I want to add a computed property called isSorted. How can I state the

Answer 1

The most flexible solution to me is a combination of NSAddict's and Wes Campaigne's answer. I.e. combine the advantage of being able to extend protocols and to pass comparator functions as arguments. This eliminates the restrictions both to use it only with arrays and to constrain it to elements conforming to Comparable protocol.

extension CollectionType
{
    func isSorted(isOrderedBefore: (Generator.Element, Generator.Element) -> Bool) -> Bool
    {
        var previousIndex = startIndex
        var currentIndex = startIndex.successor()

        while currentIndex != endIndex
        {
            if isOrderedBefore(self[previousIndex], self[currentIndex]) == false
            {
                return false
            }

            previousIndex = currentIndex
            currentIndex = currentIndex.successor()
        }

        return true
    }
}

This can be used on any Collection type and sorting criteria can be defined according to your needs.