[core, ios, macos] Added layers and sources properties to MGLStyle

Added new layers and sources properties to MGLStyle that contain all the style’s layers and sources, respectively. These properties are KVC-compliant with all the mutable to-many methods. Layers are ordered from topmost to bottommost, for consistency with Cocoa APIs where front/first means top and back/last means bottom.

Also added storage for mbgl::style::Source in MGLSource proper for wrapping AnnotationSource. Until the style finishes loading, its name property is set to nil.

Fixes #6003.

1 files changed, 3 insertions, 0 deletions

diff --git a/platform/darwin/src/MGLStyleLayer.mm.ejs b/platform/darwin/src/MGLStyleLayer.mm.ejs
index f8b8305616..8febd69a20 100644
--- a/platform/darwin/src/MGLStyleLayer.mm.ejs
+++ b/platform/darwin/src/MGLStyleLayer.mm.ejs
@@ -120,6 +120,9 @@ namespace mbgl {
 - (void)removeFromMapView:(MGLMapView *)mapView
 {
     auto removedLayer = mapView.mbglMap->removeLayer(self.identifier.UTF8String);
+    if (!removedLayer) {
+        return;
+    }
     _pendingLayer = std::move(reinterpret_cast<std::unique_ptr<mbgl::style::<%- camelize(type) %>Layer> &>(removedLayer));
     _rawLayer = _pendingLayer.get();
 }