iOS - Custom UISwitch in Class - ios

Question

version: Xcode 12.3
My project uses UISwitch heavily. Therefore, I am creating a custom Class to customize it.
I would like to set UISwitch default thumbTintColor and backgroundColor, and update these colors when the switch is togged on (isOn property).
I've found a solution but it does not work when I return to the viewController. The switch doesn't retain the setting:
subviews[0].subviews[0].backgroundColor = UIColor.white
I can't set isOn because it's read-only property.
Is there anyway that I can set the value change? I want something like below in the customSwitch Class:
Switch off: thumbTintColor = UIColor.yellow, backgroundColor =
UIcolor.black
Switch on: thumbTintColor = UIColor.red, backgroundColor =
UIcolor.white
below is my custom Class, can anyone help? thanks.
import Foundation
#IBDesignable
class CustomSwitch: UISwitch {
private var previousValue = false
private var returnPreviousValue = false
override var isOn: Bool {
return returnPreviousValue ? previousValue : super.isOn
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
previousValue = isOn
addTarget(self, action: #selector(_didChange), for: .valueChanged)
}
override init(frame: CGRect) {
super.init(frame: frame)
addTarget(self, action: #selector(_didChange), for: .valueChanged)
}
override func setOn(_ on: Bool, animated: Bool) {
super.setOn(on, animated: animated)
previousValue = on
}
#objc func _didChange() {
let isOn = self.isOn
if isOn == previousValue {
return
}
returnPreviousValue = true
willChangeValue(forKey: "on")
returnPreviousValue = false
previousValue = isOn
didChangeValue(forKey: "on")
}
}

Answer 1

Code
#IBDesignable
class CustomSwitch: UISwitch {
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.initialSetUp()
}
convenience init() {
self.init(frame: .zero)
}
override init(frame: CGRect) {
super.init(frame: frame)
self.initialSetUp()
}
private func initialSetUp() {
self.addTarget(self, action: #selector(refreshUI), for: .valueChanged)
self.refreshUI()
}
#objc private func refreshUI() {
/// Be aware that this is more of a hack than a solution
/// And can break in any upcoming release
let targetSubview = self.subviews.first?.subviews.first
if self.isOn {
self.thumbTintColor = .red
targetSubview?.backgroundColor = .white
}
else {
self.thumbTintColor = .yellow
targetSubview?.backgroundColor = .black
}
}
}
Usage
let customSwitch = CustomSwitch()
self.view.addSubview(customSwitch)
customSwitch.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
customSwitch.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),
customSwitch.centerYAnchor.constraint(equalTo: self.view.centerYAnchor),
])