title: Is there a way to have a single icon along a way?
body: <p>I'm using a <code>MGLSymbolStyleLayer</code> to render icons on a way on my mapbox instance on iOS.
  My problem right now is the frequency that icon is drawn: I tried all the values of MGLSymbolPlacement as value for <code>styleLayer.symbolPlacement</code> but none of them seems to satisfy my needs.
  As you can see in the two attached images sometimes the red X are placed once along the way, sometimes more than once.
  Using MGLSymbolPlacement.Point I achieved to have a single X on a way, but it would only be at its beginning.</p>
  <p>My goal is to have a single X on each Way and placed at its middle point, half way between start and end.
  Is it achievable in any way?</p>
  <p>Thanks</p>
  <p><a href="https://i.stack.imgur.com/sA5EJ.jpg" rel="nofollow noreferrer">1</a>
  <a href="https://i.stack.imgur.com/v70t7.png" rel="nofollow noreferrer">2</a></p>
  <pre><code>let styleLayer = MGLSymbolStyleLayer(identifier: identifier, source: source)
      styleLayer.sourceLayerIdentifier = sourceLayerIdentifier
  
      styleLayer.symbolPlacement = NSExpression(forConstantValue: MGLSymbolPlacement.line.rawValue)
      styleLayer.iconImageName = NSExpression(forConstantValue: imageName)
      styleLayer.iconScale =
          NSExpression(format: &quot;mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)&quot;,
                       [13: 0.0, 15: 0.45])
      styleLayer.iconRotationAlignment = NSExpression(forConstantValue: MGLIconRotationAlignment.viewport.rawValue)
      styleLayer.iconAllowsOverlap = NSExpression(forConstantValue: true)
      styleLayer.keepsIconUpright = NSExpression(forConstantValue: true)
      styleLayer.iconOpacity =
          NSExpression(format: &quot;mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)&quot;,
                       [13: 0, 14: 1])
  </code></pre>