How to add the vertical alignment between Button and label programmatically - swift

Question

Rather creating a Xib file and loading it into tableview. I am creating a label and button in Header view.
var btnTimeZone = UIButton(type: .Custom)
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
self.btnTimeZone.titleLabel?.font = UIFont.boldSystemFontOfSize(14.0)
self.btnTimeZone.backgroundColor = UIColor.clearColor()
self.btnTimeZone.setTitleColor(UIColor.blackColor(), forState: .Normal)
self.btnTimeZone.addTarget(self, action: #selector(self.selectClicked), forControlEvents: UIControlEvents.TouchUpInside)
}
override func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let headerView = UIView(frame: CGRect(x: 0, y: 0, width: tableView.frame.width, height: 150))
headerView.layer.borderWidth = 2
headerView.layer.borderColor = UIColor.whiteColor().CGColor
headerView.backgroundColor = ClientConfiguration.primaryUIColor()
let myLabel = UILabel()
myLabel.frame = CGRectMake(0, 0, tableView.frame.width - 70, 30)
myLabel.font = UIFont.boldSystemFontOfSize(10)
myLabel.backgroundColor = ClientConfiguration.primaryUIColor()
myLabel.textColor = UIColor.whiteColor()
myLabel.textAlignment = .Left
myLabel.text = "please Select your Time Zone"
let frame = CGRectMake(0, 0,headerView.frame.width , 50)
self.btnTimeZone.frame = frame
headerView.addSubview(myLabel)
headerView.addSubview(self.btnTimeZone)
return headerView
}
I want label above button in header view but I am not able to this..??
how can I do this..??

Answer 1

You can use something like the following to add a layout constraint via code:
let top = NSLayoutConstraint(item:myLabel, attribute: NSLayoutAttribute.top, relatedBy: NSLayoutRelation.equal, toItem:headerView, attribute: NSLayoutAttribute.top, multiplier:1.0, constant:0)
headerView.addConstraint(top)
Of course the issue would be that one constraint alone might not be enough and you'd need to add others to control the spacing between the label and the button and to also control the horizontal spacing for the elements.