Swift Insert Element At Specific Index

Question

I'm doing a project that has an online streaming of music.

I have an array of object called Song - Each song in that array of Song has a URL from SoundCloud.
Fast enumerate each song and then call the SoundCloud Resolve API to get the direct stream URL of each song. And store each direct url into an Array and load to my Player.

This seems to be really easy, but the #2 step is asynchronous and so each direct URL can be stored to a wrong index of array. I'm thinking to use the Insert AtIndex instead of append so I made a sample code in Playground cause all of my ideas to make the storing of direct URL retain its order, didn't work successfully.

var myArray = [String?]()

func insertElementAtIndex(element: String?, index: Int) {

    if myArray.count == 0 {
        for _ in 0...index {
            myArray.append("")
        }
    }

    myArray.insert(element, atIndex: index)
}

insertElementAtIndex("HELLO", index: 2)
insertElementAtIndex("WORLD", index: 5)

My idea is in this playground codes, it produces an error of course, and finally, my question would be: what's the right way to use this insert atIndex ?

Damien Romito · Accepted Answer · 2017-02-13 14:23:33Z

41

Very easy now with Swift 3:

// Initialize the Array
var a = [1,2,3]

// Insert value '6' at index '2'
a.insert(6, atIndex:2)

print(a) //[1,2,6,3]

answered Feb 13, 2017 at 14:23

Damien Romito

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2 Comments

Martyn Chamberlin Over a year ago

Failing to check that the index is legitimate will result in "Index out of range" when trying to access an index that's greater than a.count - 1. In this respect @Shades answer is superior.

Awais Fayyaz Over a year ago

if array is of String type, this error occurs Cannot convert value of type 'Int' to expected argument type 'String.Index'

Shades · Accepted Answer · 2017-10-20 19:29:34Z

29

This line:

if myArray.count == 0 {

only gets called once, the first time it runs. Use this to get the array length to at least the index you're trying to add:

var myArray = [String?]()

func insertElementAtIndex(element: String?, index: Int) {

    while myArray.count <= index {
        myArray.append("")
    }

    myArray.insert(element, atIndex: index)
}

edited Oct 20, 2017 at 19:29

answered Aug 14, 2016 at 13:59

Shades

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1 Comment

Martyn Chamberlin Over a year ago

I would rewrite the whole loop conditional this way: while myArray.count <= index

Deepak Tagadiya · Accepted Answer · 2019-01-23 04:54:06Z

4

swift 4

func addObject(){
   var arrayName:[String] = ["Name0", "Name1", "Name3"]
   arrayName.insert("Name2", at: 2)
   print("---> ",arrayName)
}

Output: 
---> ["Name0","Name1", "Name2", "Name3"]

edited Jan 23, 2019 at 4:54

answered Sep 27, 2017 at 9:33

Deepak Tagadiya

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