title: alloc a string and giving value directly
body: <p>Can any one tell the difference between:</p>
  
  <pre><code>NSString* myStr = @"Some value";
  </code></pre>
  
  <p>and</p>
  
  <pre><code>NSString* myStr = [[NSString alloc] initWithString:@""];
  </code></pre>
  
  <p>why i should alloc a string    even i can give some value directly..?</p>