title: What is the difference between using the iphonesimulator sdk and the macosx sdk in the Swift REPL?
body: <p>You can run the Swift REPL with a couple of different options for the <code>--sdk</code> option. You can run:</p>
  
  <pre><code>xcrun swift -v -sdk $(xcrun --show-sdk-path --sdk iphonesimulator)
  </code></pre>
  
  <p>or </p>
  
  <pre><code>xcrun swift -v -sdk $(xcrun --show-sdk-path --sdk macosx)
  </code></pre>
  
  <p>There is also </p>
  
  <pre><code>xcrun swift -v -sdk $(xcrun --show-sdk-path --sdk iphoneos)
  </code></pre>
  
  <p>Which doesn't seem to work very well and causes lots of errors. <br/>
  How will my output differ when using the iphonesimulator sdk vs the macosx sdk?</p>