Swift Array of class : how to find index in a method of the class

Question

Let's consider the following code :

Class AClass : SKNode
{
    func AFunction ()
    {
        // Some code
    }
}

var AnArrayOfAClass[AClass]()

AnArrayOfAClass[x].AFunction

How can I know in AFunction the value of the index when I call the method AFunction (index is x in the example of call I want to do like in the last line of code just above) ? Is there a way to avoid to pass it as an argument of AFunction ?

Thx

J.

No worries :) I meant where is it being used in relation to the instance of AClass that is calling it? A function or a closure can "capture" values outside of themselves, but only other values that are in the same "scope" as the function. Sorry, I don't know how to describe it better in a comment, but I don't think it is possible to answer without knowing the scope in which the array and the function are being called... — Aaron Rasmussen
– Aaron Rasmussen, Commented Jan 9, 2015 at 21:30
The ‘AnArrayOfAClass‘ array is a global variable declared outside of any specific scope (i.e. not in a function or class) and used at various levels in the code. The 'AFunction' method is called inside the didBeginContact of a SKScene object — Jonah Begood
– Jonah Begood, Commented Jan 9, 2015 at 21:58

Aaron Rasmussen · Accepted Answer · 2015-01-09 22:44:47Z

1

I'm not sure if this will work because I'm still not certain of the scope issue, but this will return the index of the first value in AnArrayOfAClass that is identical to the object calling the function:

class AClass {
    func aFunction() {

        //  This maps AnArrayOfAClass to an array of Bool values depending
        //  on whether or not the value at the index === the object calling the function
        //  and then returns the index of the first true that it encounters:

        if let index = find(anArrayOfAClass.map({ $0 === self }), true) {
            println(index)
        }
    }
}

var anArrayOfAClass = [AClass]()

let aClass = AClass()

anArrayOfAClass += [aClass]

anArrayOfAClass[0].aFunction()   //  If everything worked, this should print "0", 
                                 //  which is the correct index of aClass

And I changed everything to camelCase where I thought it was appropriate - no offense intended :)

edited Jan 9, 2015 at 22:44

answered Jan 9, 2015 at 22:39

Aaron Rasmussen

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2 Comments

Aaron Rasmussen Over a year ago

And if you make AClass conform to Equatable, you can use find directly without having to do the map first.

Jonah Begood Over a year ago

Works perfectly, thanks ! I just have now to figure out why and how it works...I'll go back to Swift 101 for that...;-)

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