Swift - Array of Any to Array of Strings

Question

How can I cast an array initially declared as container for Any object to an array of Strings (or any other object)? Example :

var array: [Any] = []
.
.
.
array = strings // strings is an array of Strings

I receive an error : "Cannot assign value of type Strings to type Any"

How can I do?

Conover

I think this is not possible. You can try casting strings as! [AnyObject] to use it in array reference. – Hydrobomb

Answer 1

You can't change the type of a variable once it has been declared, so you have to create another one, for example by safely mapping Any items to String with flatMap:

var oldArray: [Any] = []
var newArray: [String] = oldArray.flatMap { String($0) }

Brightwork

Answer 2

Updated to Swift 5

var arrayOfAny: [Any] = []
var arrayOfStrings: [String] = arrayOfAny.compactMap { String(describing: $0) }

Epicarp

Answer 3

You can use this synatic sugar grammar. Still one line of code :)

var arr: [Any] = []
var strs = [String]()
arr = strs.map {$0 as! [String]}

Hensley

In my test in playground, I didn't have to cast it to [String]. Is it really needed? And I think you mean strs.map instead of arr.map? :) – Stricture

I think that question is "can compiler see arr as [String]" like you have re-declared it. Btw I haven't tested this code. – Hydrobomb

@Stricture No. you don't need cast again to [String]. I often make this for reading purpose. – Hensley

This answer makes little sense. This takes an empty array of strings and tries to map each string by force-casting each string to a String array. That will fail for a couple of reasons. – Plover

Answer 4

It can be so annoying to declare that I've resorted to declaring the data in a pList file and then simply reading it in to the variable.

You can use `contentsOfFile.

Here's a decent link to a solution: https://mcmap.net/q/1164167/-swift-5-how-to-read-variables-in-plist-files `

Tuxedo