Quicksort in Swift (Not in-place)

[Playground]Quicksort_caching.swift

import Cocoa

func quicksort(array:Int[])->Int[] {
    
    var less = Int[](), equal = Int[](), greater = Int[]()
    
    if array.count > 1{
        let pivot = array[0]
        
        for x in array{
            switch(x){
                case (let v) where v < pivot:
                    less.append(v)
                case (let v) where v > pivot:
                    greater.append(v)
                default:
                    equal.append(x)
            }
        }
        return (quicksort(less) + equal + quicksort(greater));
    }else{
        return array;
    }
}

var random = [22,19,3,1,123];
var sorted = quicksort(random);