Find X-value position of a label inside a view in Swift

Question

I want to calculate the distance between x-value of two squares positioned in a view.

I did not work because in the frame there is also the y-value and do not know how to select only one. how can I add the x-values from the position of the squares?

var redSquare: UIView = UIView()
var blueSquare: UIView = UIView()
var difference : Double = 0.0

func calc() {
difference = redSquare.frame - blueSquare.frame  
}

Answer 1

difference = Double(redSquare.frame.origin.x - blueSquare.frame.origin.x)