Demo how to pass array by reference in swift

arrayPassByValue.playground

//: Playground - noun: a place where people can play

import UIKit

class Foo {
    class ArrayWrapper{
        var array:[Bool] = [false]
        subscript(index: Int) ->Bool {
        get{
            return array[index]
        }
        set(newValue){
            array[index]=newValue
        }
        }
    }
    var array:[Bool]
    var nsArray:NSMutableArray
    var arrayWrapper:ArrayWrapper
    var inoutArray:[Bool]
    init(){
        array = [false]
        nsArray = NSMutableArray()
        nsArray.addObject(false)
        arrayWrapper = ArrayWrapper()
        inoutArray = [false]
    }
    class Bar {
        var array:[Bool]
        var nsArray:NSMutableArray
        var arrayWrapper:ArrayWrapper
        init(array:[Bool], nsArray:NSMutableArray, arrayWrapper:ArrayWrapper){
            self.array = array
            self.nsArray = nsArray
            self.arrayWrapper = arrayWrapper
        }
        func change(inout inoutArray:[Bool]){
            self.array[0] = true
            self.nsArray.replaceObjectAtIndex(0, withObject: true)
            self.arrayWrapper[0] = true
            inoutArray[0] = true
        }
    }
    func change(){
        var b = Bar(array: array, nsArray: nsArray, arrayWrapper: arrayWrapper)
        b.change(&inoutArray)
    }
}
var foo = Foo()
foo.array           //[false]
foo.nsArray         //[0]
foo.arrayWrapper    //{[false]}
foo.inoutArray      //[false]
foo.change()
foo.array           //[false]
foo.nsArray         //[1]
foo.arrayWrapper    //{[true]}
foo.inoutArray      //[true]

While an array is passed by value, a class (along with its properties) is already passed by reference. This is so convoluted. If you're going to use an enclosing custom class anyway (as opposed to switching directly to NSMutableArray, which is a reference type), all you need to do is make it hold an array, and make the class conform to the Collection protocol, and finally add the functions you'd normally use on an array -- like append( ), insert( ), remove( ), which all should call the corresponding functions on the array property.