title: problem with declare a global variable in objective c
body: <p>i have a global variable in 1 of the class like 
  classA.h</p>
  
  <pre><code>const NSString *global;
  </code></pre>
  
  <p>classA.m</p>
  
  <pre><code>global=[array objectAtIndex:0];//a array store sort of string
  </code></pre>
  
  <p>and in another class i want to call this global variable</p>
  
  <p>classB.m</p>
  
  <pre><code>import "class.h"
  
  NSLog(@"%@",global);
  </code></pre>
  
  <p>but it doesnt work,i know when i jus assigned a value directly to my global variable instead of from another variable it will work but can somebody show me how to make it achieve from a array?</p>