How to stable sort an array in swift?

Question

I've been using the sort() function but it mixes up the relative order.

This is how my code looks.

recipes.sort { $0.skill.value <= $1.skill.value }

Swift API says that:

The sorting algorithm is not stable. A nonstable sort may change the relative order of elements that compare equal.

How can I change this so that the relative order stays the same as before?

Answer 1

let sortedArray = (recipes as NSArray).sortedArray(options: .stable, usingComparator: { (lhs, rhs) -> ComparisonResult in
    let lhs = (lhs as! Recipe)
    let rhs = (rhs as! Recipe)
    if lhs.skill.value == rhs.skill.value {
        return ComparisonResult.orderedSame
    } else if lhs.skill.value < rhs.skill.value {
        return ComparisonResult.orderedAscending
    } else {
        return ComparisonResult.orderedDescending
    }
})

Took from here: https://medium.com/@cocotutch/a-swift-sorting-problem-e0ebfc4e46d4