Add a subview to a parent container view and resize the parent to wrap the child

addSubview.swift

func addSubview(subView:UIView, toView parentView:UIView) {
         parentView.addSubview(subView)
         var viewBindingsDict = [String: AnyObject]()
         viewBindingsDict["subView"] = subView
         parentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[subView]|", options: [], metrics: nil, views: viewBindingsDict))
         parentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[subView]|", options: [], metrics: nil, views: viewBindingsDict))
 }