Setting values of a class for example UIButton - swift

Question

I am lacking some basic understandings.
Today I wanted to subclass some UIView and I looked in to the UIButton definition, but I can not figure out how it works.
In the UIButton definition are properties like:
open var adjustsImageWhenHighlighted: Bool
open var adjustsImageWhenDisabled: Bool
When using an UIButton it does not matter when the values of the UIButton get set, it always gets configured the correct way same with tableView or any other UIKit classes.
I made a example:
class customView: UIView {
var shouldSetupConstraints = true
var addAdditionalSpacing = true
var elements: [String]? {
didSet{
if addAdditionalSpacing == false {
doSomething()
}
}
}
func doSomething() {
}
override init(frame: CGRect) {
super.init(frame: frame)
setUpLayout()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func updateConstraints() {
if(shouldSetupConstraints) {
// AutoLayout constraints
shouldSetupConstraints = false
}
super.updateConstraints()
}
func setUpLayout() {
}
}
Using CustomView:
lazy var customV: CustomView = {
let v = CustomView()
v.addAdditionalSpacing = true
v.elements = ["One","Two"]
return v
}()
lazy var customV2: CustomView = {
let v = CustomView()
v.elements = ["One","Two"]
v.addAdditionalSpacing = true
return v
}()
So if I am using CustomView it makes a difference in which order I set it up, I understand why but I do not understand in which way I have to design my classes so I can set the values whenever I want, except with different if didSet configurations. Why do the properties in UIButton do not have any setters, how do the values get set in that case?
Any links to documentations are appreciated as well.

Answer 1

First of all, in a UIButton you can take control of the didSet property observer for existing properties like this:
override var adjustsImageWhenDisabled: Bool {
didSet {
doStuff()
}
}
Secondly, in your class scenario you might consider passing the parameters in the constructor:
init(shouldSetupConstraints: Bool = true, var addAdditionalSpacing = true)
This way the properties will be available for you whenever you need them.
Let me know if this helps.