title: Swift - How to make sure label following slider's thumbnail?
body: <p>I need to develop custom UISlider using swift. The problem is I don't know how to make sure label following slider's thumbnail like following below:</p>
  
  <p><img src="https://i.stack.imgur.com/8x267.png" alt="enter image description here"></p>
  
  <p>My code so far</p>
  
  <pre><code>import Foundation
  import UIKit
  
  class Slider: UISlider {
  
      required init(coder aDecoder: NSCoder) {
          super.init(coder: aDecoder)
          self.layer.borderColor = UIColor.redColor().CGColor
          self.layer.borderWidth = 0.2
          self.tintColor = UIColor.redColor()
      }
  }
  </code></pre>