automatic constraints to a label inside xib swift - ios

Question

I have a nib file I created for a custom view to be loaded into a ViewController. The custom view has:
.background image that fills the whole view (I'm using it as a background)
.label inside that I need to be placed in a specific location based on the size of the background image.
I managed to resize the background image based on the size of the screen using AutoLayout in Storyboard. It can shrink with "Aspect Fit".
But I want to change the constraints of the label with the same ratio as the background image resized. Meaning, if the background image shrinks by half, I want the constraints of the label to change by half. This way, they will always show up at the same spot with respect to the image.
But the constraints I created in the storyboard for the label stay constant and I can not figure out how to manipulate the constraints for the label programatically.
here is the code for the custom class that defines the custom XIB view:
import UIKit
#IBDesignable class TestView: UIView {
var view: UIView!
var nibName = "TestView"
#IBOutlet weak var backImage: UIImageView!
#IBOutlet weak var upcomingLabel: UILabel!
#IBInspectable var Background: UIImage? {
get {
return backImage.image
}
set(Background) {
backImage.image = Background
}
}
#IBInspectable var maintenance: String? {
get {
return upcomingLabel.text
}
set(maintenance) {
upcomingLabel.text = maintenance
}
}
//MARK - Implement both CustomView initializers: init(coder:) and init(frame:)
override init(frame: CGRect) {
super.init(frame: frame)
xibSetup()
}
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
xibSetup()
}
func xibSetup() {
view = loadViewFromNib()
view.frame = bounds
addSubview(view)
}
func loadViewFromNib() -> UIView {
let bundle = NSBundle(forClass: self.dynamicType)
let nib = UINib(nibName: nibName, bundle: bundle)
let view = nib.instantiateWithOwner(self, options: nil) [0] as! UIView
return view
}
}
And here is how I'm adding the view in the View controller:
import UIKit
class TestVC: UIViewController {
#IBOutlet weak var customViewContainer: UIView!
override func viewDidLoad() {
super.viewDidLoad()
let customView = TestView()
customView.setTranslatesAutoresizingMaskIntoConstraints(false)
customViewContainer.addSubview(customView)
//Add constraint to the view
let viewDictionary = ["custom": customView, "view": view]
let constraintH = NSLayoutConstraint.constraintsWithVisualFormat("H:|[custom]", options: NSLayoutFormatOptions(0), metrics: nil, views: viewDictionary)
let constraintV = NSLayoutConstraint.constraintsWithVisualFormat("V:|[custom]", options: NSLayoutFormatOptions(0), metrics: nil, views: viewDictionary)
let constraintWidth = NSLayoutConstraint(item: customView, attribute: .Width, relatedBy: .Equal, toItem: customViewContainer, attribute: .Width, multiplier: 1, constant: 0)
let constraintHeight = NSLayoutConstraint(item: customView, attribute: .Height, relatedBy: .Equal, toItem: customViewContainer, attribute: .Height, multiplier: 1, constant: 0)
view.addConstraints(constraintH as [AnyObject])
view.addConstraints(constraintV as [AnyObject])
view.addConstraint(constraintWidth)
view.addConstraint(constraintHeight)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
I'm loosing my mind over this, help!