title: Xamarin studio fails build when setting nib file for ios 6 or later
body: <p>I am in the middle of upgrading nib files to be compatible with both 6 and ios 7. However if I set the property "builds for" to ios 6.1 or later in xcode, xamarin studio(version 4.0.13 - build 38) gives an "error CS1566: Error reading resource file". If I set it back to "ios 7" it works again. I want to set the nib to 6.1 because I want to be able to use delta values in xcode - interfacebuilder.</p>
  
  <p>Any suggestion to what I have forgotten is highly appreciated. </p>
  
  <p>To answer Oliver, I am not using autolayout because than the option of using ios 6/7 delta values is removed in interfacebuilder. My issues is the statusbar in ios 7, i want it to move 20 px down when ios 7 and not do it in ios 6 :)</p>