title: How to set frame of UIButton
body: <p>There's UIButton, button1 for example. I want to set its frame in the code.<br>
  I tried <code>button1.frame = CGRectMake(20,20,50,50);</code> but I've seen no effect. And I try to output the width in an alert:
  <code>alert.message = [NSString stringWithFormat:@"%f", button1.frame.size.width]</code>, and the value is 0.
  I don't know why.</p>