More SymbolLayer properties + sourceLayerIdentifier support + zoom levels + local image support

[hactar]

Sorry for conglomerate of different changes - these were missing features we needed for a testflight release.

• Added multiple properties to the SymbolLayer so one can set more of the text attributes that were missing.
• Added support for specifying zoom levels. It works, but there was some zoom level code already, so please verify that what I added is as intended.
• Added support for dynamic images on the SymbolLayer. It is similar to the code you had, but uses "keyPath" instead of "attribute" to access the feature property.
• Added sourceLayerIdentifier (https://maplibre.org/maplibre-native/ios/latest/documentation/maplibre/mlnvectorstylelayer/sourcelayeridentifier), needed to be able to access a specific source layer combined with MLNSource.

Here is a screenshot from our app, using all these features (notice the text, halos, dynamic images created locally from sf symbols, etc - all this is loaded from a source in the style json):

Tests do not pass, I will update the PR once https://github.com/stadiamaps/maplibre-swiftui-dsl-playground/pull/41 is merged.

[hactar]

So I tried adding the example to the the example layers file, but for some reason it crashes in the Preview here (and only here). If I create an app project and add the same code, there is no crash and the code works both in preview mode and in the app.

I have no idea why this may be, I'm blaming it on the package not being a real app, but I have no proof for this. I have attached a screenshot of this working, as well as a demo app to this comment. Maybe someone else knows whats going on, or else we just don't provide an un-commented in example...

MapLibreDSLThing.zip

[ianthetechie]

🤯 whoa! What on earth?? Previews are weird, yeah, but.... okay. That's interesting. That also probably explains why, after trying several different things a few weeks ago, I never got anything that worked for image matching! I was only ever testing in the previews.

I'll take a look, but I believe that means this is probably mergeable as-is and we'll have to raise an issue upstream after collecting some more details on the crash.