var initialConfig: UIButton.Configuration = .borderless()
initialConfig.title = "Click me!"
initialConfig.buttonSize = .medium
initialConfig.background.strokeWidth = 2
initialConfig.background.strokeColor = .systemBlue

let button = UIButton(configuration: initialConfig)
button.translatesAutoresizingMaskIntoConstraints = false

button.configurationUpdateHandler = { button in
    var currentConfig = button.configuration
    
    if button.isHighlighted {
        currentConfig?.background.backgroundColor = .systemBlue
        currentConfig?.baseForegroundColor = .white
    } else {
        currentConfig?.background.backgroundColor = .clear
        currentConfig?.baseForegroundColor = nil
    }
    
    button.configuration = currentConfig
}