This script is for Illustrator CS6. It outputs iOS standard and @2x assets from layers. It fits the artboard to the items on the layer, including items without fill and stroke.

Output iOS Assets.jsx

// Output iOS Assets.jsx
// 2013 Todd Linkner
// License: none (public domain)
// v1.0
//
// This script is for Illustrator CS6. It outputs iOS standard and @2x 
// assets from layers. 
//
// Script concept and saveToRes function based on herkulano's 
// Illustrator Script for Mobile: https://github.com/herkulano
//
// Install to /Applications/Adobe Illustrator CS6/en_US/Scripts/Mobile

// bring Illustrator into focus
#target illustrator

var folder = Folder.selectDialog();
var document = app.activeDocument;

if (document && folder) {
  processLayers();
}

function processLayers() {
  var i, n,  // Counters
      layer, // Source document
      newItem, newLayer, newGroup, newDocument; // Destination document

  for (i = document.layers.length - 1; i >= 0; i--) {
    layer = document.layers[i];

    if (!layer.locked) {
      newDocument = app.documents.add(DocumentColorSpace.RGB);
      newLayer = newDocument.layers.add();
      newGroup = newDocument.groupItems.add()
      for (var n = layer.pageItems.length-1; n >= 0; n--)  {
        // Copy the page items on the layer to a new document
        newItem = layer.pageItems[n].duplicate(newLayer, ElementPlacement.PLACEATBEGINNING);
        newItem.moveToBeginning(newGroup);
      }
      // Make sure they are on the arboard
      newGroup.left = 0;
      newGroup.top = 0;
      newDocument.selectObjectsOnActiveArtboard();
      // Fit the artboard to the layer contents (including un-filled items)
      newDocument.fitArtboardToSelectedArt(
          activeDocument.artboards.getActiveArtboardIndex()
      );
      newDocument.artboards[0].name = layer.name;
      saveToRes(newDocument,100, "");
      saveToRes(newDocument,200, "@2x");
      newDocument.close(SaveOptions.DONOTSAVECHANGES);
    }
  }
  alert("Done!");
}

function saveToRes(doc, scaleTo, densitySuffix) {
  var i, ab, 
      file, options;

  for (i = doc.artboards.length - 1; i >= 0; i--) {
    doc.artboards.setActiveArtboardIndex(i);
    ab = doc.artboards[i];
    file = new File(folder.fsName + "/" + ab.name + densitySuffix + ".png");
    options = new ExportOptionsPNG24();
    options.antiAliasing = true;
    options.transparency = true;
    options.artBoardClipping = true;
    options.verticalScale = scaleTo;
    options.horizontalScale = scaleTo;
    doc.exportFile(file, ExportType.PNG24, options);
  }
}