title: Change appearance of uitextfield
body: <p>I have a textfield I need to customize.
  I want the border to only show on the bottom of the textfield (instead of a rectangle, I want a borderless textfield with just a line under the text).</p>
  
  <p>What I tried : </p>
  
  <p>In <code>viewDidLoad</code>, I tried changing the <code>.borderStyle</code> property, then noticed I could in IB
  I looked at the .layer property.
  tried to set a background image that would be white with a line on the bottom but there is no backgroundImage property or <code>textField.view</code> 
  I tried creating a view and appending it to <code>textField.subViews (UIView[])</code>.</p>
  
  <p>I tried sub-classing <code>UITextField</code>, that did not work (because I did not know what method to put the modifications in, if there even is one).</p>