CODEWITHSUNDEEP
arraysclassswiftinitialization
Imanou Petit
Imanou Petit

Reputation: 92409

Set type of an array when initializing a class

I have a class called Controller that contains one Array property. Right now, my class is declared like that:

class Controller {
    var myArray: [AnyObject] 

    init(bool: Bool) {
        if bool == true {
            myArray = [10, 11, 12]
        } else {
            myArray = ["Yo", "Ya", "Yi"]
        }
    }
}

The problem that I have with this code is that myArray is still (of course) of type [AnyObject] after my class initialization. Thus, every time I need to get an object out of myArray, I have to cast its type (Int or String) just like this:

let controller = Controller(bool: false)
let str = controller.array[0] as String

I want to be able to write let str = controller.array[0] //str: String without having to cast the real type of the objects inside myArray. Is there a way to do so? Do I have to use lazy init, struct, generic types?

Here is a attempt in pseudo code:

class Controller {
    var myArray: Array<T> //Error: use of undeclared type 'T'

    init(bool: Bool) {
        if bool == true {
            myArray = [10, 11, 12] as [Int] //myArray: Array<Int>
        } else {
            myArray = ["Yo", "Ya", "Yi"] as [String] //myArray: Array<String>
        }
    }
}

Upvotes: 0

Views: 91

Answers (3)

Chris Wagner
Chris Wagner

Reputation: 21003

So as Oscar and Elijah pointed out (up votes to them), I am just trying to be a little more verbose here. You need to declare the generic, T, when you define the class.

This would mean you need to define what that generic's type is at initialization of the class.

class Foo<T> {
    var items = [T]()
}

let stringFoo = Foo<String>()

stringFoo.items.append("bar")
stringFoo.items[0] = "barbar"

stringFoo.items                 // ["barbar"]



let intFoo = Foo<Int>()

intFoo.items.append(1)
intFoo.items[0] = 11

intFoo.items                    // [11]

So in your case, rather than passing a Bool for the init method, just define the generic's type at initialization instead.

Upvotes: 3

Oscar Swanros
Oscar Swanros

Reputation: 19969

class Controller<T> {
    var array: Array<T> = []

    ...
}

Upvotes: 2

Elijah Igny
Elijah Igny

Reputation: 65

class Controller<T> //You missed that T, right?
{ 
    var myArray: Array<T>
    /* initialization stuff */
}

var c = Controller<String>()
c.myArray[0] = "Hey!"
let str = c.myArray[0] //String, eventually!

Upvotes: 3

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