Dismiss UIView border drawn as CGRect around CALayer.frame - swift

Question

I'm adding borders to views like this:
extension UIView {
func addTopBorderWithColor(color: UIColor, width: CGFloat) {
let border = CALayer()
border.backgroundColor = color.cgColor
border.frame = CGRect(x:0,y: 0, width:self.frame.size.width, height:width)
self.layer.addSublayer(border)
}
}
in viewDidLoad:
textLbl.addTopBorderWithColor(color: UIColor.white, width: 1)
in viewWillAppear:
textLbl.text = "placeholder text \(variableLengthText)"
How can I dismiss the border I've drawn using the above extension?

Answer 1

In other views (for instance a ToolBar) as a sloppy hack, I would just write over the border with one matching the background color of the object so it didn’t overlap (for instance on a screen orientation change)
Well, that was always wrong, so the first thing to do is to stop doing it.
This has nothing to do with viewDidDisappear or viewWillAppear. The signal that the view is changing size is that its layoutSubviews is called. So you could implement layoutSubviews to remove the border layer and add a new one at the new size.
But it would be even better to add a subview to the label, consisting of a clear background except for the border. That way, the subview could be configured using constraints to grow and shrink together with the label automatically with no need for any code. Here's a screencast demonstrating that implementation; the red line is the right border:

Answer 2

While #matt's storyboard solution looks elegant, I'm unable to implement it. I did however get it to work by setting the layer.name field in the extension and checking for it in ViewWillLayoutSubviews
extension UIView {
func addTopBorderWithColor(color: UIColor, width: CGFloat) {
let border = CALayer()
border.backgroundColor = color.cgColor
border.frame = CGRect(x:0,y: 0, width:self.frame.size.width, height:width)
border.name = "topBorder"
self.layer.addSublayer(border)
}
In ViewWillLayoutSubviews I call:
if self.textLbl.layer.sublayers != nil {
for layer in textLbl.layer.sublayers! {
if layer.name == "rightBorder" || layer.name == "leftBorder" || layer.name == "topBorder" {
layer.removeFromSuperlayer()
}
}
}
In ViewDidLayoutSubviews I call:
textLbl.addTopBorderWithColor(color: UIColor.white, width: 1.5)