title: Programatic Constraints Not Obeyed
body: <p>I run the below code on a button press, however the bottom constraint does not seem to be obeyed. The subview (bandCardView) overflows the bottom of the parent view (formVw). How can I make these constraints obeyed?</p>
  
  <pre><code> @objc private func cardBtnTouch(){
          self.bandAccountView?.bankBtn.setSelected(selected: false)
          self.bandAccountView?.cardBtn.setSelected(selected: true)
  
          self.bandAccountView?.selectLbl.isHidden = true
          for subview in self.bandAccountView!.formVw.subviews{
              subview.removeFromSuperview()
          }
          self.bandAccountView!.formVw.addSubview(bandCardView!)
          self.bandAccountView!.formVw.addConstraint(NSLayoutConstraint(item: self.bandAccountView!.formVw, attribute: NSLayoutAttribute.top, relatedBy: NSLayoutRelation.equal, toItem: bandCardView!, attribute: NSLayoutAttribute.top, multiplier: 1.0, constant: 0.0))
          self.bandAccountView!.formVw.addConstraint(NSLayoutConstraint(item: bandCardView!, attribute: NSLayoutAttribute.bottom, relatedBy: NSLayoutRelation.equal, toItem: self.bandAccountView!.formVw, attribute: NSLayoutAttribute.bottom, multiplier: 1.0, constant: 0.0))
          self.bandAccountView!.formVw.addConstraint(NSLayoutConstraint(item: bandCardView!, attribute: NSLayoutAttribute.leading, relatedBy: NSLayoutRelation.equal, toItem: self.bandAccountView!.formVw, attribute: NSLayoutAttribute.leading, multiplier: 1.0, constant: 0.0))
          self.bandAccountView!.formVw.addConstraint(NSLayoutConstraint(item: self.bandAccountView!.formVw, attribute: NSLayoutAttribute.trailing, relatedBy: NSLayoutRelation.equal, toItem: bandCardView!, attribute: NSLayoutAttribute.trailing, multiplier: 1.0, constant: 0.0))
      }
  </code></pre>