[ios] Address feedback

4 files changed, 34 insertions, 38 deletions

diff --git a/platform/darwin/src/MGLShapeSource.h b/platform/darwin/src/MGLShapeSource.h
index f11e45722b..73171dfe17 100644
--- a/platform/darwin/src/MGLShapeSource.h
+++ b/platform/darwin/src/MGLShapeSource.h
@@ -45,19 +45,27 @@ FOUNDATION_EXTERN MGL_EXPORT const MGLShapeSourceOption MGLShapeSourceOptionClus
  An `NSDictionary` object where the key is an `NSString`. The dictionary key will
  be the feature attribute key. The resulting attribute value is
  aggregated from the clustered points. The dictionary value is an `NSArray`
- consisting of two objects.
+ consisting of two `NSExpression` objects.
 
  The first object determines how the attribute values are accumulated from the
- cluster points. The resulting value is assigned to the specified attribute key.
- You can use one of the following:
-
- * An `[NSExpression expressionForConstantValue:]` containing a single function string, such as `sum` or `max`, which takes at least two operands.
- * An `NSExpression` that takes two expression arguments: `featureAccumulated` and
- another valid expression.
+ cluster points. It is an `NSExpression` with an expression function that accepts
+ two or more arguments (such as `sum` or `max`). The arguments should be
+ `featureAccumulated` and the previously defined feature attribute key. The
+ resulting value is assigned to the specified attribute key.
 
  The second `NSExpression` in the array determines which
  attribute values are accessed from individual features within a cluster.
 
+ ```swift
+ let key = "sumValue"
+ let firstExpression = NSExpression(format: "sum({ $featureAccumulated, %@ })", key)
+ let secondExpression = NSExpression(forKeyPath: "magnitude")
+ let clusterPropertiesDictionary = [key : [firstExpression, secondExpression]]
+ 
+ let options : [MGLShapeSourceOption : Any] = [.clustered : true,
+                                            .clusterProperties: clusterPropertiesDictionary]
+ ```
+
  This option corresponds to the
  <a href="https://www.mapbox.com/mapbox-gl-style-spec/#sources-geojson-clusterProperties"><code>clusterProperties</code></a>
  source property in the Mapbox Style Specification.
diff --git a/platform/darwin/src/MGLShapeSource.mm b/platform/darwin/src/MGLShapeSource.mm
index 8bf0a3d3e5..3820fe9d60 100644
--- a/platform/darwin/src/MGLShapeSource.mm
+++ b/platform/darwin/src/MGLShapeSource.mm
@@ -107,28 +107,19 @@ mbgl::style::GeoJSONOptions MGLGeoJSONOptionsFromDictionary(NSDictionary<MGLShap
                             format:@"MGLShapeSourceOptionClusterProperties member value requires array of two objects."];
             }
 
-            // reduceExpression could be either a string of operator, or a valid NSExpression
-            if (![expressionsArray.firstObject isKindOfClass:[NSExpression class]]) {
+            // reduceExpression should be a valid NSExpression
+            NSExpression *reduceExpression = expressionsArray[0];
+            if (![reduceExpression isKindOfClass:[NSExpression class]]) {
                 [NSException raise:NSInvalidArgumentException
                 format:@"MGLShapeSourceOptionClusterProperties array value requires two expression objects."];
             }
-            NSExpression *reduceOperator = expressionsArray[0];
-            NSExpression *reduceExpression;
-            if (reduceOperator.expressionType == NSConstantValueExpressionType) {
-                // If reduceOperator is a string, prepare a full NSExpression before parsing
-                NSString *reduceString = [NSString stringWithFormat:@"%@({ $featureAccumulated, %@})", reduceOperator.constantValue, key];
-                reduceExpression =  [NSExpression expressionWithFormat:reduceString];
-            } else {
-                reduceExpression = expressionsArray[0];
-            }
-
             auto reduce = MGLClusterPropertyFromNSExpression(reduceExpression);
             if (!reduce) {
                 [NSException raise:NSInvalidArgumentException
                             format:@"Failed to convert MGLShapeSourceOptionClusterProperties reduce expression."];
             }
 
-            // mapExpression shall be a valid NSExpression
+            // mapExpression should be a valid NSExpression
             NSExpression *mapExpression = expressionsArray[1];
             if (![mapExpression isKindOfClass:[NSExpression class]]) {
                 [NSException raise:NSInvalidArgumentException
diff --git a/platform/darwin/test/MGLDocumentationExampleTests.swift b/platform/darwin/test/MGLDocumentationExampleTests.swift
index 9fbb0cc329..9505b144d9 100644
--- a/platform/darwin/test/MGLDocumentationExampleTests.swift
+++ b/platform/darwin/test/MGLDocumentationExampleTests.swift
@@ -554,7 +554,21 @@ class MGLDocumentationExampleTests: XCTestCase, MGLMapViewDelegate {
         
         XCTAssertNotNil(attributedExpression)
     }
-    
+
+    func testMGLShapeSourceOptionClusterProperties() {
+
+
+        //#-example-code
+        let key = "sumValue"
+        let firstExpression = NSExpression(format: "sum({ $featureAccumulated, %@ })", key)
+        let secondExpression = NSExpression(forKeyPath: "magnitude")
+        let clusterPropertiesDictionary = [key : [firstExpression, secondExpression]]
+
+        let options : [MGLShapeSourceOption : Any] = [.clustered : true,
+                                                   .clusterProperties: clusterPropertiesDictionary]
+        //#-end-example-code
+
+    }
     // For testMGLMapView().
     func myCustomFunction() {}
 }
diff --git a/platform/ios/app/MBXViewController.m b/platform/ios/app/MBXViewController.m
index 2b35bd697b..82a68e074a 100644
--- a/platform/ios/app/MBXViewController.m
+++ b/platform/ios/app/MBXViewController.m
@@ -2202,23 +2202,6 @@ CLLocationCoordinate2D randomWorldCoordinate() {
     // that a device with an English-language locale is already effectively
     // using locale-based country labels.
     _localizingLabels = [[self bestLanguageForUser] isEqualToString:@"en"];
-
-    NSURL *url = [NSURL URLWithString:@"https://www.mapbox.com/mapbox-gl-js/assets/earthquakes.geojson"];
-
-    NSExpression *reduceExpression1 =  [NSExpression expressionForConstantValue:@"sum"];
-
-    NSExpression *mapExpression1 = [NSExpression expressionForKeyPath:@"mag"];
-    NSArray *expressArray1 = @[reduceExpression1, mapExpression1];
-
-    MGLShapeSource *source = [[MGLShapeSource alloc] initWithIdentifier:@"earthquakes" URL:url options:@{
-    MGLShapeSourceOptionClustered: @(YES),
-    MGLShapeSourceOptionClusterRadius: @(15),
-    MGLShapeSourceOptionClusterProperties: @{@"sumVal" : expressArray1 }}];
-    [mapView.style addSource:source];
-    MGLSymbolStyleLayer *clusterLayer = [[MGLSymbolStyleLayer alloc] initWithIdentifier:@"clusteredPortsNumbers" source:source];
-    clusterLayer.text = [NSExpression expressionWithFormat:@"CAST(sumVal, 'NSString')"];
-    [self.mapView.style addLayer:clusterLayer];
-
 }
 
 - (BOOL)mapView:(MGLMapView *)mapView shouldChangeFromCamera:(MGLMapCamera *)oldCamera toCamera:(MGLMapCamera *)newCamera {