Array of objects contains all identical values inside the objects

Question

I'm new in Swift and I got problem using an array of objects.

class myClass {
    var test: Int?

    static func testFunc() {
        var array = [myClass] (count: 30, repeatedValue: myClass())
        for i in 0...20 {
            array[i].test = i*2
        }

        for a in 0...20 {
            println(array[a].test)
        }
    }
}

I really have no idea what could be wrong here but my result is always 40 instead of 0 to 40:

Optional(40)
Optional(40)
Optional(40)
etc......

Does anyone know how to solve this problem? Almost seems a bit like a bug.

Duncan C · Accepted Answer · 2015-05-05 23:16:54Z

3

The count:repeatedValue: initializer installs the exact same object in every position of the array.

So when you change array[0].test to some value, you are changing the value stored in the single myClass instance that is shared at all indexes of the array. Look at index 19 and you see the same myClass objet, with the changed value.

So use a loop to initialize your array:

var array = [myClass]()

for (i in 1...20)
{
  let anItem = myClass()
  anItem.test = i
   array.append(anItem)
}

edited May 5, 2015 at 23:16

answered May 5, 2015 at 22:40

Duncan C

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2 Comments

nilskober Over a year ago

Thanks, that solved my problem. But it has to be `var array = [myClass]()´ in the first line.

Duncan C Over a year ago

Oh yea. Forgot that bit.

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