2 files changed, 21 insertions, 0 deletions
diff --git a/platform/darwin/src/MGLShapeSource.h b/platform/darwin/src/MGLShapeSource.h
index e5c62515e5..c80c329cbc 100644
--- a/platform/darwin/src/MGLShapeSource.h
+++ b/platform/darwin/src/MGLShapeSource.h
@@ -96,6 +96,18 @@ FOUNDATION_EXTERN MGL_EXPORT const MGLShapeSourceOption MGLShapeSourceOptionBuff
 FOUNDATION_EXTERN MGL_EXPORT const MGLShapeSourceOption MGLShapeSourceOptionSimplificationTolerance;
 
 /**
+ An `NSNumber` object containing a Boolean enabling or disabling calculating line distance metrics. 
+ 
+ Set this property to `YES` in order for the `MGLLineStyleLayer.lineGradient` property to have its intended effect.
+ The default value is `NO`.
+ 
+ This option corresponds to the
+ <a href="https://www.mapbox.com/mapbox-gl-js/style-spec/#sources-geojson-lineMetrics"><code>lineMetrics</code></a>
+ source property in the Mapbox Style Specification.
+ */
+FOUNDATION_EXTERN MGL_EXPORT const MGLShapeSourceOption MGLShapeSourceOptionLineDistanceMetrics;
+
+/**
  `MGLShapeSource` is a map content source that supplies vector shapes to be
  shown on the map. The shapes may be instances of `MGLShape` or `MGLFeature`,
  or they may be defined by local or external
diff --git a/platform/darwin/src/MGLShapeSource.mm b/platform/darwin/src/MGLShapeSource.mm
index 1425269012..6512d07a66 100644
--- a/platform/darwin/src/MGLShapeSource.mm
+++ b/platform/darwin/src/MGLShapeSource.mm
@@ -20,6 +20,7 @@ const MGLShapeSourceOption MGLShapeSourceOptionMaximumZoomLevel = @"MGLShapeSour
 const MGLShapeSourceOption MGLShapeSourceOptionMaximumZoomLevelForClustering = @"MGLShapeSourceOptionMaximumZoomLevelForClustering";
 const MGLShapeSourceOption MGLShapeSourceOptionMinimumZoomLevel = @"MGLShapeSourceOptionMinimumZoomLevel";
 const MGLShapeSourceOption MGLShapeSourceOptionSimplificationTolerance = @"MGLShapeSourceOptionSimplificationTolerance";
+const MGLShapeSourceOption MGLShapeSourceOptionLineDistanceMetrics = @"MGLShapeSourceOptionLineDistanceMetrics";
 
 mbgl::style::GeoJSONOptions MGLGeoJSONOptionsFromDictionary(NSDictionary<MGLShapeSourceOption, id> *options) {
     auto geoJSONOptions = mbgl::style::GeoJSONOptions();
@@ -80,6 +81,14 @@ mbgl::style::GeoJSONOptions MGLGeoJSONOptionsFromDictionary(NSDictionary<MGLShap
         geoJSONOptions.cluster = value.boolValue;
     }
 
+    if (NSNumber *value = options[MGLShapeSourceOptionLineDistanceMetrics]) {
+        if (![value isKindOfClass:[NSNumber class]]) {
+            [NSException raise:NSInvalidArgumentException
+                        format:@"MGLShapeSourceOptionLineDistanceMetrics must be an NSNumber."];
+        }
+        geoJSONOptions.lineMetrics = value.boolValue;
+    }
+
     return geoJSONOptions;
 }