Swift operator `subscript` []

Question

I am beginner with the Swift having no advance knowledge with operators.

I have the following class

class Container {    var list: [Any] = []; } 

I want to implement the operator subscript [] in order to access the data from list.

I need something like this:

var data: Container = Container() var value = data[5] // also     data[5] = 5 

Also I want to be able to write something like this:

data[1][2] 

Is it possible considering that element 1 from Container is an array?

Thanx for help.

Answer 1

It looks like there are 2 questions here.

1. How can I enable subscripting on my own custom class?

To enable subscripting on your class Container you need to implement the subscript computed property like this.

class Container {     private var list : [Any] = [] // I made this private      subscript(index:Int) -> Any {         get {             return list[index]         }         set(newElm) {             list.insert(newElm, atIndex: index)         }     } } 

Now you can use it this way.

var container = Container() container[0] = "Star Trek" container[1] = "Star Trek TNG" container[2] = "Star Trek DS9" container[3] = "Star Trek VOY"  container[1] // "Star Trek TNG" 

2. Can I access one element of Container that supports subscripting writing something like data[1][2]?

If we use your example no, you cannot. Because data[1] returns something of type Any. And you cannot subscript Any.

But if you add a cast it becomes possible

var container = Container() container[0] = ["Enterprise", "Defiant", "Voyager"] (container[0] as! [String])[2] // > "Voyager"