Circular array, iterate to all element in array starting at any given index

CircularArrayViewController.swift

//
//  CircularArrayViewController.swift
//  Samples
//
//  Created by VikasK on 22/07/19.
//  Copyright © 2019 Vikaskore Software. All rights reserved.
//

import UIKit

class CircularArrayViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        var testArray = [1,2,3,4,5,6,7,8,9]
        
        let reOrderedArray  = rotate(array: &testArray, index: 8)
        print("Reordered Array Elements: \(reOrderedArray)")
    }
    
    func rotate(array: inout [Int], index: Int) -> Array<Int> {
        //The resulting array will be same array
        if index == 0 || array.count <= 1 {
            return array
        }
        
        // Calculate the effective number to re-arrange
        let length = array.count
        let rotations = (length + index) % length
        
        let leftPart = Array(array[0..<rotations])
        
        let rightPart = Array(array[rotations..<length])
        
        array = rightPart + leftPart
        
        return array
    }
}

/* Output
 rotate(array: &testArray, index: 8)
 Reordered Array Elements: [9, 1, 2, 3, 4, 5, 6, 7, 8]
 rotate(array: &testArray, index: 3)
 Reordered Array Elements: [4, 5, 6, 7, 8, 9, 1, 2, 3]
 rotate(array: &testArray, index: 0)
 Reordered Array Elements: [1, 2, 3, 4, 5, 6, 7, 8, 9]
 rotate(array: &testArray, index: 10)
 Reordered Array Elements: [2, 3, 4, 5, 6, 7, 8, 9, 1]
 */