title: How to keep the UISearchBar's placeholder left-aligned
body: <p>I find the iOS system(7.0+) keep the placeholder of UISearchBar center-aligned,but left-aligned in 6.0- version. I want to keep UISearchBar's placeholder left-aligned in all versions of iOS. then,how can I handle with it?</p>
  
  <p>I attempt to append whitespace character to the UISearchBar's placeHolder, It seems to  resolve the problem, But I want to know whether exist elegant method to handle this problem. Is there god can teach me to end the problem? </p>