title: objective define constants according to device type
body: <p>Hi I am building one Iphone application in which I am defining few constants. I know many people ask same question but I am not able to figure it out. So my problem is like this. I am defining my constant values in one file say <code>constants.m</code> and <code>constants.h</code>. SO my <code>constant.h</code> looks like :</p>
  
  <pre><code>@interface Constants : NSObject
      //  UI CONSTANTS
      extern int FONT_SIZE_14;
   @end
  </code></pre>
  
  <p>And my <code>constants.m</code> looks like :</p>
  
  <pre><code>@implementation Constants
  
      //  UI CONSTANTS.
  
      #if (IS_IPAD)
          int FONT_SIZE_14 = 18;
      #else
          int FONT_SIZE_14 = 14;
      #endif
  @end
  </code></pre>
  
  <p>So it works fine without any error but it always takes only value 14. If it is running on ipad it is not taking 18 value. Am doing anything wrong. Need some help. Thank you. </p>