How to put reference to variable instead of variable value into an array

Question

In swift how do I put a pointer into an array?

I have several arrays, in all of them I make reference to a variable and when I change it I need it to update in all the other arrays.

Edit: Basically i have an array

var ExampleArray     : NSMutableArray = [
    0,
    "TestString",
    ["*"],
    9,
]

What i want to do is add a pointer to the array so it would be like

var ExampleArray     : NSMutableArray = [
    0,
    "TestString",
    ["*"],
    9,
    //Pointer Here
]

The pointer is to a string that features in many arrays, if update its value in one array i want it to update in all the arrays

How do i declare this?

Thanks

Vatsal · Accepted Answer · 2015-04-04 18:44:39Z

1

It literally can't get any simpler than this:

var value: Int = 0
var array: [UnsafeMutablePointer<Int>] = []

withUnsafeMutablePointer(&value, array.append)

But maybe you want to store multiple types, in which case the following should suffice:

var value: Int = 0
var array: [UnsafeMutablePointer<Void>] = []

public func getVoidPointer<T>(inout x: T) -> UnsafeMutablePointer<Void>
{
    return withUnsafeMutablePointer(&x, { UnsafeMutablePointer<Void>($0) })
}

array.append(getVoidPointer(&value))

edited Apr 4, 2015 at 18:44

answered Apr 4, 2015 at 18:39

Vatsal

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3 Comments

nhgrif Over a year ago

This answer is correct enough. It's worth noting though that the this will only accept pointers to Int (obviously). If we use UnsafeMutablePointer<Void>, we can accept pointers to any type. +1 though.

Vatsal Over a year ago

@nhgrif: Well noted. I've updated my answer to reflect your observations.

Display Name Over a year ago

I've updated my question, i know its really obvious and I'm certainly over thinking it

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