Storing a reference to array in swift

I want to pass an array to an object and store a reference to this array. I want to be able to modify this array within this object and make sure that it's modified everywhere else.

Here is what I am trying to accomplish (how the code doesn't work)

class Foo {   var foo : Array<Int>   init(foo: Array<Int>) {      self.foo = foo   }   func modify() {      foo.append(5)   }}var a = [1,2,3,4]let bar = Foo(a)bar.modify()print(a) // My goal is that it will print 1,2,3,4,5

My findings so far

A) The array (by default) are passed strange way. It's a reference until you modify an array length. As soon as you modify a length it will be copied and modified. As result, if I append or delete anything from it in the object it won't be seen outside

B) I can use inout on a function parameter. This will allow me to modify it within this function. However, as soon as I will try to assign it to some object member I am again struck by A)

C) I can wrap an array in some Container class. This probably is the cleanest way. However, I serialize/deserialize these objects and I would rather not put it in Container (because I will have to work around some things for serialization and deserialization and sending it to the server).

Are there anything else? Am I missing some Swift construct which allows me to do that?