Wait until style has loaded before doing things to it

[bsudekum]

Attempts to fix the black lines in #338.

I think in some cases,

mapbox-navigation-ios/MapboxNavigation/RouteMapViewController.swift

Lines 345 to 358 in eab11c9

	if streetsSources.isEmpty {
	let source = MGLVectorSource(identifier: "mapboxStreetsv7", configurationURL: URL(string: "mapbox://mapbox.mapbox-streets-v7")!)
	style.addSource(source)
	streetsSources.append(source)
	}
	if let mapboxSteetsSource = streetsSources.first, style.layer(withIdentifier: roadLabelLayerIdentifier) == nil {
	let streetLabelLayer = MGLLineStyleLayer(identifier: roadLabelLayerIdentifier, source: mapboxSteetsSource)
	streetLabelLayer.sourceLayerIdentifier = "road_label"
	streetLabelLayer.lineOpacity = MGLStyleValue(rawValue: 1)
	streetLabelLayer.lineWidth = MGLStyleValue(rawValue: 20)
	streetLabelLayer.lineColor = MGLStyleValue(rawValue: .white)
	style.insertLayer(streetLabelLayer, at: 0)
	}

could be causing a race condition if the style is not fully loaded.

/cc @frederoni @1ec5 @zijiazhai

[1ec5]

If the style hasn’t finished loading, we can’t manipulate the style in order to query it for street names, but we should still run the rest of this method in order to snap the user’s location to the route.

In fact, that’s what the code already does: it checks for a non-nil style before manipulating the style. style would be nil until the style has finished loading.

[1ec5]

So you’re actually right about needing to track hasFinishedLoadingStyle separately. style is nil until the style finishes loading, but sources such as Streets may take a little longer to load. But instead of guard, we need to modify the existing giant if statement.

[bsudekum]

@1ec5 fixed