title: Xcode 4.2 + c++0x/libc++ cannot find iostream
body: <p>I'm using Macbook 1g, Snow Leopard.</p>
  
  <p>Few days ago i installed xcode 4.2 and made a test project for c++0x.</p>
  
  <p>I set LLVM 3.0 as c++ compiler, C++ Language Dialect as C++0x and C++ Standard Library as libc++.</p>
  
  <p>but when building, error occured.</p>
  
  <pre><code>"iostream" file not found
  </code></pre>
  
  <p>I find it most bewildering. How can I solve this problem?</p>