UIStepper

class ViewController: UIViewController {
    
    var stepper:UIStepper!
    var label:UILabel!

    override func viewDidLoad() {
        
        super.viewDidLoad()
        
        stepper = UIStepper(frame: CGRect(x: 60.0, y: 60.0, width: 100.0, height: 100.0))
        stepper.maximumValue = 10
        stepper.minimumValue = 1
        stepper.stepValue = 0.5 // 每次增减的值
        stepper.isContinuous = true // 连续按动
        stepper.wraps = true // 到最大值时是否循环
        stepper.addTarget(self, action: #selector(stepperValueChanged(stepper:)), for: .valueChanged)
        self.view.addSubview(stepper)
        
        label = UILabel(frame: CGRect(x: 60.0, y: 200.0, width: 100.0, height: 200.0))
        label.font = UIFont.systemFont(ofSize: 10.0)
        label.text = "当前值为: \(stepper.value)"
        self.view.addSubview(label)
    }
    
    @objc func stepperValueChanged(stepper:UIStepper) ->Void {
        label.text = "当前值为: \(stepper.value)"
    }
    
}