StackView -Swap Buttons in ArrangedSubviews

Question

I have a UIStackView initially set with 4 buttons. If I need to later swap out the last button with a new button or back to the initial button, how can I do that?

lazy var stackView: UIStackView = {
    let sv = UIStackView()
    sv.axis = .horizontal
    sv.distribution = .fillEqually
    sv.alignment = .fill
    return sv
}()

// ...
var bt4: UIButton!
var bt5: UIButton!

// viewDidLoad
func configureStackView() {

    view.addSubview(stackView)

    stackView.addArrangedSubview(bt1)
    stackView.addArrangedSubview(bt2)
    stackView.addArrangedSubview(bt3)
    stackView.addArrangedSubview(bt4)

    // place stackView at bottom of scene
}

func swapLastButtonInStackViewWithNewButton(_ val: Bool) {

    if val {

        // if true replace bt4 in stackView with bt5

    } else {

        // if false replace bt5 in stackView with bt4
    }
}

Answer 1

You can store the arrange of stack subviews like this:

    lazy var stackViewArrangedSubviews = stackView.arrangedSubviews {
        didSet {
            setStackViewSubviews(with: stackViewArrangedSubviews)
        }
    }

and then

    func setStackViewSubviews(with subviews: [UIView]) {
        stackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
        subviews.forEach { stackView.addArrangedSubview($0) }
    }

and finally implement the swap function like this:

    func swapLastButtonInStackViewWithNewButton(_ val: Bool) {
        
        if val {
            stackViewArrangedSubviews[3] = bt5
            // if true replace bt4 in stackView with bt5
            
        } else {
            stackViewArrangedSubviews[3] = bt4
            // if false replace bt5 in stackView with bt4
        }
    }

This is not perfect, You can improve the code by your need.