value type of constant in Swift in layout anchors - autolayout

Question

Just to know the difference between 10 (for example) and view.frame.height/10 (where view.frame.height is 100)
I put textView.frame.height/3 instead of of 25 in paddingTop (see code below) and the value of paddingTop becomes 0
I tried this .....
extension UIView
{ func anchor( top: NSLayoutYAxisAnchor?,
left: NSLayoutXAxisAnchor?,
bottom: NSLayoutYAxisAnchor?,
right: NSLayoutXAxisAnchor?,
paddingTop: CGFloat,
paddingLeft: CGFloat,
paddingBottom: CGFloat,
paddingRight: CGFloat,
width: CGFloat,
height: CGFloat )
{ translatesAutoresizingMaskIntoConstraints = false
if let top = top { self.topAnchor.constraint(equalTo: top, constant: paddingTop).isActive = true }
if let left = left { self.leftAnchor.constraint(equalTo: left, constant: paddingLeft).isActive = true }
if let bottom = bottom { self.bottomAnchor.constraint(equalTo: bottom, constant: -paddingBottom).isActive = true }
if let right = right { self.rightAnchor.constraint(equalTo: right, constant: -paddingRight).isActive = true }
if width != 0 { widthAnchor.constraint(equalToConstant: width).isActive = true }
if height != 0 { heightAnchor.constraint(equalToConstant: height).isActive = true }
}
...
view.addSubview(textView)
textView.anchor(top: topView.bottomAnchor, left: view.leftAnchor, bottom: nil, right: nil, paddingTop: 10, paddingLeft: 10, paddingBottom: 0, paddingRight: 10, width: 0, height: view.frame.height/4)
textView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
textView.addSubview(label)
label.anchor(top:textView.topAnchor, left: textView.leftAnchor, bottom: nil, right: nil, paddingTop: 25, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 0, height:textView.frame.height/5)
counterLabel.centerXAnchor.constraint(equalTo: descrizioneTextView.centerXAnchor).isActive = true

Answer 1

So the reason why you're experiencing that problem is because at the moment you're initialising the view, the value (view.frame.height) is 0 and you can't get view.frame.height/4.
Since you're working with UIView, Try to set the padding top in this method :
override func layoutSubviews() {
super.layoutSubviews()
}