Layout Constraints Added Programmatically to UITableViewCell - ios

Question

I am attempting to reproduce the constraints in this screenshot, which are applied to a static UITableViewCell:
Here is the code I'm using to try to do this:
#IBOutlet weak var cellTest: UITableViewCell!
override func viewDidLoad() {
super.viewDidLoad()
cellTest.backgroundColor = UIColor.yellowColor()
let vw = UIView()
vw.backgroundColor = UIColor.greenColor()
cellTest.contentView.addSubview(vw)
cellTest.contentView.translatesAutoresizingMaskIntoConstraints = false
vw.translatesAutoresizingMaskIntoConstraints = false
let constraintWidth = NSLayoutConstraint(item: vw, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 400)
let constraintHeight = NSLayoutConstraint(item: vw, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 150)
let constraintCentreX = NSLayoutConstraint(item: vw, attribute: .CenterX, relatedBy: .Equal, toItem: vw.superview!, attribute: .CenterX, multiplier: 1, constant: 0)
let constraintCentreY = NSLayoutConstraint(item: vw, attribute: .CenterY, relatedBy: .Equal, toItem: vw.superview!, attribute: .CenterY, multiplier: 1, constant: 0)
cellTest.contentView.addConstraints([constraintWidth, constraintHeight, constraintCentreX, constraintCentreY ])
}
However, below is the unexpected output, with the view in the top left instead of centred. Any help is much appreciated as I've spent quite some time trying to figure this out:

Answer 1

I needed to add constraints to the cell's contentView, as well. These are added to the cell itself.
Code and screenshot below.
#IBOutlet weak var cellTest: UITableViewCell!
override func viewDidLoad() {
super.viewDidLoad()
cellTest.backgroundColor = UIColor.yellowColor()
let vw = UIView()
vw.backgroundColor = UIColor.greenColor()
cellTest.contentView.addSubview(vw)
cellTest.contentView.translatesAutoresizingMaskIntoConstraints = false
vw.translatesAutoresizingMaskIntoConstraints = false
let bottomConstraint = NSLayoutConstraint(item: cellTest.contentView, attribute: NSLayoutAttribute.Bottom, relatedBy: NSLayoutRelation.Equal, toItem: cellTest.contentView.superview!, attribute: NSLayoutAttribute.Bottom, multiplier: 1, constant: 0)
let trailingConstraint = NSLayoutConstraint(item: cellTest.contentView, attribute: NSLayoutAttribute.Trailing, relatedBy: NSLayoutRelation.Equal, toItem: cellTest.contentView.superview!, attribute: NSLayoutAttribute.Trailing, multiplier: 1, constant: 0)
let topConstraint = NSLayoutConstraint(item: cellTest.contentView, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: cellTest.contentView.superview!, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0)
let leadingConstraint = NSLayoutConstraint(item: cellTest.contentView, attribute: NSLayoutAttribute.Leading, relatedBy: NSLayoutRelation.Equal, toItem: cellTest.contentView.superview!, attribute: NSLayoutAttribute.Leading, multiplier: 1, constant: 0)
cellTest.addConstraints([bottomConstraint, trailingConstraint, topConstraint, leadingConstraint])
let constraintWidth = NSLayoutConstraint(item: vw, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 200)
constraintWidth.priority = 1000
let constraintHeight = NSLayoutConstraint(item: vw, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 80)
constraintHeight.priority = 1000
let constraintCentreX = NSLayoutConstraint(item: vw, attribute: .CenterX, relatedBy: .Equal, toItem: vw.superview!, attribute: .CenterX, multiplier: 1, constant: 0)
constraintCentreX.priority = 1000
let constraintCentreY = NSLayoutConstraint(item: vw, attribute: .CenterY, relatedBy: .Equal, toItem: vw.superview!, attribute: .CenterY, multiplier: 1, constant: 0)
constraintCentreY.priority = 1000
cellTest.contentView.addConstraints([constraintWidth, constraintHeight, constraintCentreX, constraintCentreY ])
}