3 files changed, 62 insertions, 1 deletions
diff --git a/platform/darwin/src/MGLLineStyleLayer.h b/platform/darwin/src/MGLLineStyleLayer.h
index 1080244bdb..a7ac7f1462 100644
--- a/platform/darwin/src/MGLLineStyleLayer.h
+++ b/platform/darwin/src/MGLLineStyleLayer.h
@@ -366,6 +366,50 @@ MGL_EXPORT
 */
 @property (nonatomic) MGLTransition lineGapWidthTransition;
 
+#if TARGET_OS_IPHONE
+/**
+ Defines a gradient with which to color a line feature. Can only be used with
+ GeoJSON sources that specify `"lineMetrics": true`.
+ 
+ This property is only applied to the style if `lineDasharray` is set to `nil`,
+ and `linePattern` is set to `nil`, and the data source requirements are met.
+ Otherwise, it is ignored.
+ 
+ You can set this property to an expression containing any of the following:
+ 
+ * Constant `UIColor` values
+ * Predefined functions, including mathematical and string operators
+ * Conditional expressions
+ * Variable assignments and references to assigned variables
+ * Interpolation and step functions applied to the `$lineProgress` variable
+ 
+ This property does not support applying interpolation or step functions to
+ feature attributes.
+ */
+@property (nonatomic, null_resettable) NSExpression *lineGradient;
+#else
+/**
+ Defines a gradient with which to color a line feature. Can only be used with
+ GeoJSON sources that specify `"lineMetrics": true`.
+ 
+ This property is only applied to the style if `lineDasharray` is set to `nil`,
+ and `linePattern` is set to `nil`, and the data source requirements are met.
+ Otherwise, it is ignored.
+ 
+ You can set this property to an expression containing any of the following:
+ 
+ * Constant `NSColor` values
+ * Predefined functions, including mathematical and string operators
+ * Conditional expressions
+ * Variable assignments and references to assigned variables
+ * Interpolation and step functions applied to the `$lineProgress` variable
+ 
+ This property does not support applying interpolation or step functions to
+ feature attributes.
+ */
+@property (nonatomic, null_resettable) NSExpression *lineGradient;
+#endif
+
 /**
  The line's offset. For linear features, a positive value offsets the line to
  the right, relative to the direction of the line, and a negative value to the
diff --git a/platform/darwin/src/MGLLineStyleLayer.mm b/platform/darwin/src/MGLLineStyleLayer.mm
index 3bad2a8b98..5cf0762475 100644
--- a/platform/darwin/src/MGLLineStyleLayer.mm
+++ b/platform/darwin/src/MGLLineStyleLayer.mm
@@ -306,6 +306,23 @@ namespace mbgl {
     return transition;
 }
 
+- (void)setLineGradient:(NSExpression *)lineGradient {
+    MGLAssertStyleLayerIsValid();
+
+    auto mbglValue = MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toPropertyValue<mbgl::style::ColorRampPropertyValue>(lineGradient);
+    self.rawLayer->setLineGradient(mbglValue);
+}
+
+- (NSExpression *)lineGradient {
+    MGLAssertStyleLayerIsValid();
+
+    auto propertyValue = self.rawLayer->getLineGradient();
+    if (propertyValue.isUndefined()) {
+        propertyValue = self.rawLayer->getDefaultLineGradient();
+    }
+    return MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toExpression(propertyValue);
+}
+
 - (void)setLineOffset:(NSExpression *)lineOffset {
     MGLAssertStyleLayerIsValid();
 
diff --git a/platform/darwin/src/MGLStyleLayer.mm.ejs b/platform/darwin/src/MGLStyleLayer.mm.ejs
index 0707e573c4..49ac04ce05 100644
--- a/platform/darwin/src/MGLStyleLayer.mm.ejs
+++ b/platform/darwin/src/MGLStyleLayer.mm.ejs
@@ -169,7 +169,7 @@ namespace mbgl {
 
 <% switch (property['property-type']) {
     case 'color-ramp': -%>
-    auto mbglValue = MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toPropertyValue<mbgl::style::ColorRampPropertyValue>(heatmapColor);
+    auto mbglValue = MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toPropertyValue<mbgl::style::ColorRampPropertyValue>(<%- objCName(property) %>);
 <%     break
     case 'data-driven':
     case 'cross-faded-data-driven': -%>