How to reverse array in Swift without using “.reverse()”?

Question

I have array and need to reverse it without Array.reverse method, only with a for loop.

var names:[String] = [\"Apple\", \"Microsof         


        

Answer 1

var rArray : [Int] = [2,5,6,8,3,8,9,10]
var ReArray = [Int]()
var a : Int = 1

func reversed (_ array: [Int]) -> [Int] {
    for i in array {
        ReArray.append(array[array.count-a])
        a += 1
    }

    rArray = ReArray

    return rArray
}

reversed(rArray)

print(rArray)

Answer 2

Here you go:

var names:[String] = ["Apple", "Microsoft", "Sony", "Lenovo", "Asus"]

var reversedNames = [String]()

for var arrayIndex = names.count - 1 ; arrayIndex >= 0 ; arrayIndex-- {
    reversedNames.append(names[arrayIndex])
}

Answer 3

This will work with any sized array.

import Cocoa

var names:[String] = [ "A", "B", "C", "D", "E","F"]
var c = names.count - 1
for i in 0...(c/2-1) { swap(&names[i],&names[c-i]) }

print(names)

Answer 4

// Swap the first index with the last index.
// [1, 2, 3, 4, 5] -> pointer on one = array[0] and two = array.count - 1
// After first swap+loop increase the pointer one and decrease pointer two until
// conditional is not true. 

func reverseInteger(array: [Int]) -> [Int]{
        var array = array
        var first = 0
        var last = array.count - 1
        while first < last {
            array.swapAt(first, last)
            first += 1
            last -= 1
        }
        return array
    }

input-> [1, 2, 3, 4, 5] return->[5, 4, 3, 2, 1]

Answer 5

Ignoring checks for emptiness..

var names:[String] = ["Apple", "Microsoft", "Sony", "Lenovo", "Asus"]

var reversedNames: [String]
reversedNames = []

for name in names {
    reversedNames.insert((name), atIndex:0)
}

Answer 6

Do you really need a for loop? If not, you can use reduce.

I guess that this is the shortest way to achieve it without reversed() method (Swift 3.0.1):

["Apple", "Microsoft", "Sony", "Lenovo", "Asus"].reduce([],{ [$1] + $0 })