title: Nature of NSString
body: <p>Such a basic question, but i don't know the answer.What exactly the difference between:</p>
  
  <pre><code>NSString *str = @"Hello";
  </code></pre>
  
  <p>and</p>
  
  <pre><code>NSString *str = [[NSString alloc] initWithString:@"Hello"];
  </code></pre>
  
  <p>When should i use each one?</p>