Swift Quicksort Algorithm

been trying to program the following Quicksort Algorithm in Swift for a while now and cannot work out the issue. [Quicksort as there are around 15,000 actual values in array]. The problem is only the left half of the array is ordered (see pic), and the method is never exited (infinite loop). Following a Java conversion from http://www.java2novice.com/java-sorting-algorithms/quick-sort/ (tested in Java and does work). Cannot work out the error.

var arr = [Int]()
var length = 0

override func viewDidLoad()
{
    super.viewDidLoad()

    arr = [5,2,4,7,2,1,3,9,10,11,7,8]
    print(arr)

    sort(inputArr: &arr);

    print(arr)
}

func sort(inputArr: inout [Int])
{

    if (inputArr.count == 0) || (inputArr == nil)
    {
        print("finished")
        return
    }

    arr = inputArr
    length = arr.count
    quicksort(low:0,high:length-1)

}

func quicksort(low: Int, high: Int)
{
    var i = low
    var j = high

    var piv = (low + (high-low))
    piv = piv / 2
    let pivot_location = arr[piv]

    print("----")

    while i <= j
    {
        while arr[i] < pivot_location
        {
            i+=1
        }
        while arr[j] > pivot_location
        {
            j-=1
        }

        if i <= j
        {
            let temp = arr[i]
            arr[i] = arr[j]
            arr[j] = temp

            i+=1
            j-=1
        }
    }

    print(arr)

    if low < j
    {
        quicksort(low: low, high: j)
    }
    if i < high
    {
        quicksort(low: i, high: high)
    }
}

Console print of array after iteration through method

Your computation of piv and pivot_location is wrong. It should be:

let piv = (low + (high - low) / 2)
let pivot_location = arr[piv]    

Note that I moved the division by two inside the previous calculation.

Output:

[5, 2, 4, 7, 2, 1, 3, 9, 10, 11, 7, 8]
[1, 2, 4, 7, 2, 5, 3, 9, 10, 11, 7, 8]
[1, 2, 3, 2, 7, 5, 4, 9, 10, 11, 7, 8]
[1, 2, 2, 3, 7, 5, 4, 9, 10, 11, 7, 8]
[1, 2, 2, 3, 7, 5, 4, 9, 10, 11, 7, 8]
[1, 2, 2, 3, 7, 5, 4, 8, 7, 11, 10, 9]
[1, 2, 2, 3, 4, 5, 7, 8, 7, 11, 10, 9]
[1, 2, 2, 3, 4, 5, 7, 8, 7, 11, 10, 9]
[1, 2, 2, 3, 4, 5, 7, 8, 7, 11, 10, 9]
[1, 2, 2, 3, 4, 5, 7, 7, 8, 11, 10, 9]
[1, 2, 2, 3, 4, 5, 7, 7, 8, 9, 10, 11]
[1, 2, 2, 3, 4, 5, 7, 7, 8, 9, 10, 11]