Can't change String Array in Swift 2 after returning it from function

Question

I have this playground example:

import UIKit

var testArray: [[String]] = [["2","2"],["1","1"]]

testArray[0][0] = "3" // Working

func getTestArray() -> [String] {

    return testArray[0]

}

var test = getTestArray()[0] = "4" // Error: Immutable Value

How can i get the reference of testArray to change it

Changing test won't change testArray!

Swift arrays are value types. Your function returns a value, not a reference to the original array. — Martin R
– Martin R, Commented Feb 13, 2018 at 9:43
@Sweeper it's for a project that uses an outdated sdk and sadly can't be updated — Jonas
– Jonas, Commented Feb 13, 2018 at 10:14

Papershine · Accepted Answer · 2018-02-13 09:47:59Z

3

getTestArray() returns a value, not a reference. Therefore, the value returned by a function cannot be edited, only variables can be changed. To change the variable, use:

var testVal = getTestArray() // get the value
testVal[0] = "4" // change the value
testArray[0] = testVal // SET the value of the reference `testArray` (change the value)

answered Feb 13, 2018 at 9:47

Papershine

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3 Comments

Jonas Over a year ago

With this solution getTestArray() would be useless. You could get testArray directly. But maybe there is no better solution

Papershine Over a year ago

@JonasSchafft To be honest, why you need such a function?

Jonas Over a year ago

Difficult to explain. But it would help me in an specific situation.

Ilya Kharabet · Accepted Answer · 2018-02-13 09:41:18Z

0

You need to assign value to test and than change it:

var test = getTestArray()
test[0] = "4"

answered Feb 13, 2018 at 9:41

Ilya Kharabet

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1 Comment

Jonas Over a year ago

Then i`m not changing testArray

Catherine · Accepted Answer · 2018-02-13 09:43:43Z

0

var test = getTestArray()
test[0] = "4"
print(test)

answered Feb 13, 2018 at 9:43

Catherine

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4 Comments

Jonas Over a year ago

Then i`m not changing testArray

Jonas Over a year ago

I need to change testArray. Not something else. Can i get the reference?

Catherine Over a year ago

They are not reference types

Catherine Over a year ago

use classes instead

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