title: Compare NSString with constant #define string: isEqualToString or ==?
body: <p>If I need to compare a NSString property with a constant string define by <code>#define</code>, can I use double equal sign?</p>
  
  <p>I know that <code>isEqualToString:</code> would work, but just wonder if <code>==</code> also works, say for the following two scenarios:</p>
  
  <p>Scenario 1:</p>
  
  <pre><code>#define BLA @"BLA"
  NSString *str1 = BLA;
  BOOL equal = self.someStr == BLA;
  </code></pre>
  
  <p>Scenario 2:</p>
  
  <pre><code>#define BLA @"BLA"
  NSString *str1 = @"BLA";
  BOOL equal = self.someStr == BLA;
  </code></pre>
  
  <p>are they the same?</p>