MGLRasterTileSource is drawn above MGLOverlay or below other unwanted layers. How do I get the z-order right on this?

I'm using Mapbox iOS SDK v6.3.0

I have an MGLOverlay on my map, but whenever I add a MGLRasterTileSource it appears above the overlay and hides it!

I have currently fixed it by randomly inserting numbers into style.insertLayer(layer, at: x)

• Inserting at 0 seemed to work, but once I switched to the default Streets map and then back to my custom tiles, the Streets map left some junk on top of my map.
• Inserting at 15 seemed to show my map tiles on top of everything and still below wherever the overlay is, but this seems pretty prone to crashing.

There must be a cleaner way of doing this right?

The default map styleURLs work fine, it's only my custom raster tiles where I have to manually edit the style to add sources and layers.

There are 2 different kinds of maps I'm loading

1. Mapbox styleURLs: These are very simple to set, as you just set the mapView.styleURL
2. Raster Tiles: These are more complex to add and you have call addSource() and addLayer() (or in my case insertLayer(layer: below:))

My initial implementation of route lines using MGLPolyline worked fine on styleURL maps, but was having trouble with raster tile maps as I described in the question.

Mapbox Support (Megan, the other answer) mentioned I should try to use MGLLineStyleLayer instead since it is more performant and I can better control the z-order since it's in the same style.layers array and I can insertLayer(below:) (which I can't seem to use with MGLPolyline).

However, once I did that, the styleURL maps no longer worked, since when I switched to that style of map, it clears out all the style layers and rebuilds it!!

So to finally solve my problem I had to re-add the MGLLineStyleLayer (and source) every time I switch to a styleURL type of map.

A GOTCHYA! Now this does work, but for some reason I couldn't cache the MGLLineStyleLayer and MGLShapeSource and re-add it directly using addSource and addLayer from the source and layers I had cached...

I had to initialize them again from scratch or Mapbox would throw an exception that I hadn't created them right. I couldn't figure out what was wrong and this was the only thing that seemed to work.

Who knows I got way off track and there is an easier solution, but this is what is working for me.