title: How to change the number of components in a UIPickerView?
body: <p>I have a <code>UITableView</code> for different datas. When the user select one row, then I will popup a <code>UIPickerView</code> to let the user select some values. And I have implemented the <code>numberOfComponentsInPickerView</code> DataSource method to return the number of components for different row in the <code>UITableView</code>. actually they are all 1.</p>
  
  <p>But now, I will download more data from the internet and add more rows in the <code>UITableView</code>. I called <code>[pickerView reloadAllComponents]</code> after finishing the downloading. I expected the <code>numberOfComponentsInPickerView</code> will be called so I can have more components in the picker view for the new rows in <code>UITableView</code>. But it's not working.</p>
  
  <p>How can I do that? thanks.</p>