title: XCode 8: basic MKMapView causes warnings
body: <p>In an XCode 8 Swift 3 project, I have a ViewController that contains nothing but a MKMapView. Whenever I segue to this ViewController, I get the following warning printout...</p>
  
  <pre><code>MyProject[2141:497518] [LogMessageLogging] 6.1 &lt;private&gt;
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  ERROR /BuildRoot/Library/Caches/com.apple.xbs/Sources/VectorKit/VectorKit-1228.30.7.17.9/GeoGL/GeoGL/GLCoreContext.cpp 1763: InfoLog SolidRibbonShader:
  ERROR /BuildRoot/Library/Caches/com.apple.xbs/Sources/VectorKit/VectorKit-1228.30.7.17.9/GeoGL/GeoGL/GLCoreContext.cpp 1764: WARNING: Output of vertex shader 'v_gradient' not read by fragment shader
  
  
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  Painter Z index: 1023 is too large (max 255)
  </code></pre>
  
  <p>I don't know why this happening nor how to resolve it. This is simply a ViewController with a map, nothing more, so I don't see why there are these problems.</p>