요약

true를 반환하면 순서를 유지하고
false를 반환하면 순서를 뒤집는다

코드

Setting

import Foundation

let arr = (1...10).map{_ in Int.random(in: 1...100)}

Ascending

let ascending = arr.sorted { prev, next in
    print("prev(\(prev)) vs next(\(next))", terminator: " ===> ")
    if prev < next {
        print("keep order")
        return true
    } else {
        print("swap order")
        return false
    }
}

Descending

let descending = arr.sorted { prev, next in
    print("prev(\(prev)) vs next(\(next))", terminator: " ===> ")
    if prev > next {
        print("keep order")
        return true
    } else {
        print("swap order")
        return false
    }
}