title: Why does a simple program import <Foundation/Foundation.h> instead of individual header files?
body: <p>I'm new to Objective-C. The Xcode generated template code contains:</p>
  
  <pre><code>#import &lt;Foundation/Foundation.h&gt;
  </code></pre>
  
  <p>When I check it at /System/Library/Frameworks/Foundation.framework/Headers, there are nearly 2 thousands header files!</p>
  
  <p>My question is, for a really simple code that use only NSString, why not import just the NSString.h file?</p>
  
  <p>Does importing the whole bunch of Foundation framework affect the performance of executables? If not, does it have some benefits?</p>