Swift - Initializing class variables which are classes

I am new to Swift. I am having trouble with declaring classes. I have the following -

class position_ 
{
    var x: Float = 0
    var y: Float = 0
}

class node_
{
    var label: String = nil
    var coordinates: position_
}

Now I can create an initializer init() in the position_ class, like this -

class position_ 
{
    var x: Float
    var y: Float
    init()
    {
        x = 0
        y = 0
    }
}

Is there anyway I can use this initializer in the node_ class? Because, without an init() function there is no way to initialize the coordinates variable in the node_ class. Or is there?
I find it hard to believe that Swift would require me to initialize each of the position_ variables again in the node_ class. In other words is there a better option than the below one?

class node_
{
    var label: String
    var coordinates: position_
    init()
    {
        name = nil
        coordinates.x = 0
        coordinates.y = 0
    }
} 

Also if I want to create another variable say "b" of type UIButton how do I initialize that? That is really what I want to do.