title: changing the x value of an image on xcode?
body: <p>after looking on the internet for aprox. 1/2 hour 
  i have come with.</p>
  
  <pre><code> -(IBAction)left
  {
      img.center.x = img.center.x floatValue]-30;
  }
  </code></pre>
  
  <p>in an ideal world this would:
  when the button is clicked it moves the image 30 pixels to the left</p>
  
  <p>however we do not live in an ideal world and so when I hit build and run it comes up with 2 errors...</p>
  
  <blockquote>
    <p>error: cannot convert to a pointer type<br>
    error: lvalue required as left operand of assignment</p>
  </blockquote>
  
  <p>any soulution or insight into the problem would be greatly recieved.</p>