title: number input with UiPickerView
body: <p>In my use case I would like to add in numbers consisting of 4 digits, like in the image. The first digit should be 0 or 1. </p>
  
  <p>My code so far is:</p>
  
  <pre><code>func numberOfComponents(in weightPickerView: UIPickerView) -&gt; Int {
      return 4
  }
  
  func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -&gt; Int {
      return loopingMargin * numbers.count
  }
  
  func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -&gt; String? {
      return numbers[row % numbers.count]
  }
  
  func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
      digits[component] = row % numbers.count
      let weightString = "\(digits[0])\(digits[1])\(digits[2])\(digits[3])"
      weightField.text = weightString
  }
  </code></pre>
  
  <p>How can I achieve that?</p>
  
  <p><a href="https://i.stack.imgur.com/5VXHJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5VXHJ.png" alt="enter image description here"></a></p>