title: How to build x86_64 GTK# applications on Xamarin studio on macOS?
body: <p>I have:</p>
  
  <ol>
  <li>mono-4.8.0.472</li>
  <li>Xamarin studio</li>
  <li>Mac OS Sierra 0.12.3</li>
  <li>gtk-sharp-2.12.42</li>
  </ol>
  
  <p>I have install Xamarin studio from package. Than I have try to build x86_64 GTK# application, and i can't... I have read that for x86_64 applications i need to compile mono from source. I have delete mono by script and compile it from tarball. So Xamarin studio not working. When I start it I have error message : "This application requires Mono 4.3 or newer."
  I try to install mono on different folders: /opt/mono/mono-4.8.0. Then i have try to do this (in mono folder):</p>
  
  <p>./autogen.sh --enable-nls=no --build=x86_64-apple-darwin --prefix=/Library/Frameworks/Mono.framework/Versions/Git --with-monotouch=yes &amp;&amp; make &amp;&amp; make install</p>
  
  <p>I also have try to change prefix to "/Library/Frameworks/Mono.framework" and have the same result.</p>
  
  <p>When I trying to change architecture of project setting I can't add x64
  (<a href="https://i.stack.imgur.com/PZTsL.png" rel="nofollow noreferrer">Select arch screen</a>). Sorry for Russian interface. I don't know how to switch to English.</p>
  
  <p>I need to build x86_64 GTK# applications on Xamarin studio. How can I do this?</p>