Root Layer      <-- myView.layer
|- Bottom Layer <-- myView.layer.sublayers[0]
|- Middle Layer <-- myView.layer.sublayers[1]
|- Top Layer    <-- myView.layer.sublayers[2]

Root Layer
|- Bottom Layer
|- Middle Layer
|- Top Layer    <-- Added filter to this layer.

self.topLayer.compositingFilter = [CIFilter filterWithName:@"CIMultiplyBlendMode"];

[self.view setWantsLayer:YES];
[self.view setLayerUsesCoreImageFilters:YES];