Merge Sort and Quick Sort Algorithms in Swift (https://swift.madnik.space/algorithms-merge-sort-and-quick-sort-in-swift)

mergesort.swift

func mergeSort<T: Comparable>(inout array:[T],p: Int, r: Int) -> [T]{
    
    var p = p

    guard r > p else{
        return array
    }
    
    var q = p + (r-p)/2
    
    mergeSort(&array, p: p, r: q)
    mergeSort(&array, p: q+1, r: r)
    
    //Now Merge  
    while q < r && p <= q {
        if array[p] > array[q+1]{
            array.insert(array.removeAtIndex(q+1), atIndex: p)
            if q < r { q+=1 }
        }
        if p <= q { p += 1 }
    }
    
    return array
}

quicksort.swift

func quickSort<T where T:Comparable>(inout array: [T],p: Int,r: Int) -> [T]{

    guard array[p...r].count > 1 else{
        return array
    }

    func partition<T where T:Comparable>(inout array: [T],pivotIndex: Int) -> Int{
        var q = p
        var i = p

        let pivot = array[pivotIndex]

        while i < r{
            if array[i] < pivot {
                array.insert(array.removeAtIndex(i), atIndex: q)
                q += 1
            }

            i += 1
        }
        array.insert(array.removeAtIndex(pivotIndex), atIndex: q)
        return q
    }

    let q = partition(&array, pivotIndex: r)
    if p < q-1 { quickSort(&array, p: p, r: q-1) }
    if q+1 < r { quickSort(&array, p: q+1, r: r) }

    return array
}

Gist contains the sample code used in article https://swift.madnik.space/algorithms-merge-sort-and-quick-sort-in-swift/index.html