callbackHell.swift

func processImageData(completionBlock: (result: Image) -> Void) {
   loadWebResource("dataprofile.txt") { dataResource in
      loadWebResource("imagedata.dat") { imageResource in
         decodeImage(dataResource, imageResource) { imageTmp in
            dewarpAndCleanupImage(imageTmp) { imageResult in
               completionBlock(imageResult)
             }
          }
       }
    }
}