The tag system for the question isn't working as the exchange change only occurs on the last button - swift

Question

Button Method
#objc func buttonFuction(){
let stacView = UIStackView()
stacView.spacing = 12
stacView.distribution = .fillEqually
stacView.axis = .horizontal
stacView.translatesAutoresizingMaskIntoConstraints = false
view!.addSubview(stacView)
buttonNames = ["One","Two","Three","Four"]
for i in 0..<buttonNames.count{
index+=i
button = Button()
button.setTitle(buttonNames[i], for: .normal)
stacView.addArrangedSubview(button)
buttons.append(button)
button.tag = index
button.addTarget(self, action: selectors[i], for: .touchUpInside)
button.addTarget(self, action: selectorsColor[i], for: .touchDown)
}
NSLayoutConstraint.activate([stacView.centerXAnchor.constraint(equalTo: view!.centerXAnchor),stacView.centerYAnchor.constraint(equalTo: view!.centerYAnchor),stacView.widthAnchor.constraint(equalToConstant: 350),stacView.heightAnchor.constraint(equalToConstant:70)])
}
Button handler methods
#objc func colorButton1(){
if button.tag == 0 {
button.backgroundColor = #colorLiteral(red: 0.1123025946, green: 1, blue: 0.03079073749, alpha: 1)
}
else {
button.backgroundColor = #colorLiteral(red: 0.7974829231, green: 0.09321228972, blue: 0.09321228972, alpha: 1)
}
}
#objc func colorButton2(){
if button.tag == 1 {
button.backgroundColor = #colorLiteral(red: 0.07117979832, green: 0.8973241221, blue: 0, alpha: 1)
}
else {
button.backgroundColor = #colorLiteral(red: 0.7312681945, green: 0.1133923198, blue: 0.06002510149, alpha: 1)
}
}
#objc func colorButton3(){
if button.tag == 2 {
button.backgroundColor = #colorLiteral(red: 0.1123025946, green: 1, blue: 0.03079073749, alpha: 1)
}
else {
button.backgroundColor = #colorLiteral(red: 0.6805654408, green: 0.1003367522, blue: 0.09689761347, alpha: 1)
}
}
#objc func colorButton4(){
if button.tag == 3 {
button.backgroundColor = #colorLiteral(red: 0.1123025946, green: 1, blue: 0.03079073749, alpha: 1)
}
else {
button.backgroundColor = #colorLiteral(red: 0.7620294414, green: 0.05229266211, blue: 0.09308676813, alpha: 1)
}
}
Every time I press the button it keeps changing colour to the last button, even after tagging each button, the colour change only occurs in the last button and not sure how to change the code to allow the colour change to happen on other button when pressed.
Thank you in advance.

Answer 1

As I said in the comments, the buttons array contains 4 items which all point – due to reference semantics – to the same instance, the lastly added Button instance. So does also the button property.
You need something like this, it creates four different Button instances and uses one action method, I don't know what the second selector does so I commented it out.
The logic: The sender parameter is the just tapped button, first set all background colors except the current button to their appropriate red colors, then set the background color of the current button to the green color. The references to the buttons are taken from the buttons array.
for i in 0..<buttonNames.count{
let button = Button()
button.setTitle(buttonNames[i], for: .normal)
stacView.addArrangedSubview(button)
buttons.append(button)
button.tag = i
button.addTarget(self, action: #selector(colorButton), for: .touchUpInside)
// button.addTarget(self, action: selectorsColor[i], for: .touchDown)
}
#objc func colorButton(_ sender : Button) {
let offColors = [#colorLiteral(red: 0.7974829231, green: 0.09321228972, blue: 0.09321228972, alpha: 1),
#colorLiteral(red: 0.7312681945, green: 0.1133923198, blue: 0.06002510149, alpha: 1),
#colorLiteral(red: 0.6805654408, green: 0.1003367522, blue: 0.09689761347, alpha: 1),
#colorLiteral(red: 0.7620294414, green: 0.05229266211, blue: 0.09308676813, alpha: 1)]
for i in 0..<4 where i != sender.tag {
buttons[i].backgroundColor = offColors[i]
}
switch sender.tag {
case 0: sender.backgroundColor = #colorLiteral(red: 0.1123025946, green: 1, blue: 0.03079073749, alpha: 1)
case 1: sender.backgroundColor = #colorLiteral(red: 0.07117979832, green: 0.8973241221, blue: 0, alpha: 1)
case 2: sender.backgroundColor = #colorLiteral(red: 0.1123025946, green: 1, blue: 0.03079073749, alpha: 1)
case 3: sender.backgroundColor = #colorLiteral(red: 0.1123025946, green: 1, blue: 0.03079073749, alpha: 1)
default: break
}
}