[ios, macos] Teach features and shapes about GeoJSON and mbgl types

MGLShape subclasses can now return NSDictionaries that represent the shapes' GeoJSON geometries. MGLFeature classes can now return NSDictionaries that represent the features as GeoJSON features. This makes it trivial to serialize iOS and macOS shapes and features into GeoJSON.

MGLFeature instances can also return a representation of themselves as an mbgl::Feature. This capability is used in a refactoring of the implementations of MGLGeoJSONSource to more efficiently transform MGLFeatures into mbgl::Features so they can be fed directly into mbgl::GeoJSONSource without having to round trip through NSJSONSerialization. The MGLFeature identifier is converted into the mbgl::identifier type based on the type of the identifier. The MGLFeature attributes are recursively converted into an mbgl::PropertyMap and each value is converted into one of the types that the PropertyMap's Value variant supports.

1 files changed, 165 insertions, 0 deletions

diff --git a/platform/darwin/test/MGLFeatureTests.mm b/platform/darwin/test/MGLFeatureTests.mm
index 1b1722f172..18c3fd16c2 100644
--- a/platform/darwin/test/MGLFeatureTests.mm
+++ b/platform/darwin/test/MGLFeatureTests.mm
@@ -158,4 +158,169 @@
     XCTAssertEqual(string, shape.attributes[@"string"]);
 }
 
+- (void)testPointFeatureGeoJSONDictionary {
+    MGLPointFeature<MGLFeaturePrivate> *pointFeature = (MGLPointFeature<MGLFeaturePrivate> *)[[MGLPointFeature alloc] init];
+    CLLocationCoordinate2D coordinate = { 10, 10 };
+    pointFeature.coordinate = coordinate;
+    
+    // A GeoJSON feature
+    // when there are no identifier or properties
+    NSDictionary *geoJSONFeature = [pointFeature geoJSONDictionary];
+    
+    // it has the correct type
+    XCTAssertEqualObjects(geoJSONFeature[@"type"], @"Feature");
+    // it has the correct geometry
+    NSDictionary *expectedGeometry = @{@"type": @"Point",
+                                       @"coordinates": @[@(coordinate.longitude), @(coordinate.latitude)]};
+    XCTAssertEqualObjects(geoJSONFeature[@"geometry"], expectedGeometry);
+    // it has no "id" key (or value)
+    XCTAssertNil(geoJSONFeature[@"id"]);
+    // it has a null representation of the properties object
+    XCTAssertEqualObjects(geoJSONFeature[@"properties"], [NSNull null]);
+    
+    // when there is a string identifier
+    pointFeature.identifier = @"string-id";
+    
+    // it has the identifier in the result
+    geoJSONFeature = [pointFeature geoJSONDictionary];
+    XCTAssertEqualObjects(geoJSONFeature[@"id"], pointFeature.identifier);
+    
+    // when there are properties
+    pointFeature.attributes = @{@"name": @"name-value"};
+    
+    // it has the properties value in the result
+    geoJSONFeature = [pointFeature geoJSONDictionary];
+    XCTAssertEqualObjects(geoJSONFeature[@"properties"], pointFeature.attributes);
+}
+
+- (void)testPolylineFeatureGeoJSONDictionary {
+    CLLocationCoordinate2D coord1 = { 0, 0 };
+    CLLocationCoordinate2D coord2 = { 10, 10 };
+    CLLocationCoordinate2D coords[] = { coord1, coord2 };
+    MGLPolylineFeature *polyLineFeature = [MGLPolylineFeature polylineWithCoordinates:coords count:2];
+    
+    // A GeoJSON feature
+    NSDictionary *geoJSONFeature = [polyLineFeature geoJSONDictionary];
+    
+    // it has the correct geometry
+    NSDictionary *expectedGeometry = @{@"type": @"LineString",
+                                       @"coordinates": @[@[@(coord1.longitude), @(coord1.latitude)],
+                                                         @[@(coord2.longitude), @(coord2.latitude)]]};
+    XCTAssertEqualObjects(geoJSONFeature[@"geometry"], expectedGeometry);
+}
+
+- (void)testPolygonFeatureGeoJSONDictionary {
+    CLLocationCoordinate2D coord1 = { 0, 0 };
+    CLLocationCoordinate2D coord2 = { 10, 10 };
+    CLLocationCoordinate2D coord3 = { 0, 0 };
+    CLLocationCoordinate2D coords[] = { coord1, coord2, coord3 };
+    MGLPolygonFeature *polygonFeature = [MGLPolygonFeature polygonWithCoordinates:coords count:3];
+    
+    // A GeoJSON feature
+    NSDictionary *geoJSONFeature = [polygonFeature geoJSONDictionary];
+    
+    // it has the correct geometry
+    NSDictionary *expectedGeometry = @{@"type": @"Polygon",
+                                       @"coordinates": @[@[@[@(coord1.longitude), @(coord1.latitude)],
+                                                         @[@(coord2.longitude), @(coord2.latitude)],
+                                                         @[@(coord3.longitude), @(coord3.latitude)]]]};
+    XCTAssertEqualObjects(geoJSONFeature[@"geometry"], expectedGeometry);
+}
+
+- (void)testMultiPointFeatureGeoJSONDictionary {
+    CLLocationCoordinate2D coord1 = { 0, 0 };
+    CLLocationCoordinate2D coord2 = { 10, 10 };
+    CLLocationCoordinate2D coord3 = { 0, 0 };
+    CLLocationCoordinate2D coords[] = { coord1, coord2, coord3 };
+    MGLMultiPointFeature *multiPointFeature = [MGLMultiPointFeature multiPointWithCoordinates:coords count:3];
+    
+    // A GeoJSON feature
+    NSDictionary *geoJSONFeature = [multiPointFeature geoJSONDictionary];
+    
+    // it has the correct geometry
+    NSDictionary *expectedGeometry = @{@"type": @"MultiPoint",
+                                       @"coordinates": @[@[@(coord1.longitude), @(coord1.latitude)],
+                                                         @[@(coord2.longitude), @(coord2.latitude)],
+                                                         @[@(coord3.longitude), @(coord3.latitude)]]};
+    XCTAssertEqualObjects(geoJSONFeature[@"geometry"], expectedGeometry);
+}
+
+- (void)testMultiPolylineFeatureGeoJSONDictionary {
+    CLLocationCoordinate2D coord1 = { 0, 0 };
+    CLLocationCoordinate2D coord2 = { 10, 10 };
+    CLLocationCoordinate2D coord3 = { 0, 0 };
+    CLLocationCoordinate2D coords[] = { coord1, coord2, coord3 };
+    
+    MGLPolyline *polyLine1 = [MGLPolyline polylineWithCoordinates:coords count:3];
+    MGLPolyline *polyLine2 = [MGLPolyline polylineWithCoordinates:coords count:3];
+    
+    MGLMultiPolylineFeature *multiPolylineFeature = [MGLMultiPolylineFeature multiPolylineWithPolylines:@[polyLine1, polyLine2]];
+    
+    // A GeoJSON feature
+    NSDictionary *geoJSONFeature = [multiPolylineFeature geoJSONDictionary];
+    
+    // it has the correct geometry
+    NSDictionary *expectedGeometry = @{@"type": @"MultiLineString",
+                                       @"coordinates": @[@[@[@(coord1.longitude), @(coord1.latitude)],
+                                                          @[@(coord2.longitude), @(coord2.latitude)],
+                                                          @[@(coord3.longitude), @(coord3.latitude)]],
+                                                        @[@[@(coord1.longitude), @(coord1.latitude)],
+                                                          @[@(coord2.longitude), @(coord2.latitude)],
+                                                          @[@(coord3.longitude), @(coord3.latitude)]]]};
+    XCTAssertEqualObjects(geoJSONFeature[@"geometry"], expectedGeometry);
+}
+
+- (void)testMultiPolygonFeatureGeoJSONDictionary {
+    CLLocationCoordinate2D coord1 = { 0, 0 };
+    CLLocationCoordinate2D coord2 = { 10, 10 };
+    CLLocationCoordinate2D coord3 = { 0, 0 };
+    CLLocationCoordinate2D coords[] = { coord1, coord2, coord3 };
+    
+    MGLPolygon *polygon1 = [MGLPolygon polygonWithCoordinates:coords count:3];
+    MGLPolygon *polygon2 = [MGLPolygon polygonWithCoordinates:coords count:3];
+    
+    MGLMultiPolygonFeature *multiPolylineFeature = [MGLMultiPolygonFeature multiPolygonWithPolygons:@[polygon1, polygon2]];
+    
+    // A GeoJSON feature
+    NSDictionary *geoJSONFeature = [multiPolylineFeature geoJSONDictionary];
+    
+    // it has the correct geometry
+    NSDictionary *expectedGeometry = @{@"type": @"MultiPolygon",
+                                       @"coordinates": @[
+                                               @[@[@[@(coord1.longitude), @(coord1.latitude)],
+                                                   @[@(coord2.longitude), @(coord2.latitude)],
+                                                   @[@(coord3.longitude), @(coord3.latitude)]]],
+                                                   @[@[@[@(coord1.longitude), @(coord1.latitude)],
+                                                   @[@(coord2.longitude), @(coord2.latitude)],
+                                                   @[@(coord3.longitude), @(coord3.latitude)]]]]};
+    XCTAssertEqualObjects(geoJSONFeature[@"geometry"], expectedGeometry);
+}
+
+- (void)testShapeCollectionFeatureGeoJSONDictionary {
+    MGLPointAnnotation *pointFeature = [[MGLPointAnnotation alloc] init];
+    CLLocationCoordinate2D pointCoordinate = { 10, 10 };
+    pointFeature.coordinate = pointCoordinate;
+    
+    CLLocationCoordinate2D coord1 = { 0, 0 };
+    CLLocationCoordinate2D coord2 = { 10, 10 };
+    CLLocationCoordinate2D coords[] = { coord1, coord2 };
+    MGLPolyline *polyline = [MGLPolyline polylineWithCoordinates:coords count:2];
+    
+    MGLShapeCollectionFeature *shapeCollectionFeature = [MGLShapeCollectionFeature shapeCollectionWithShapes:@[pointFeature,
+                                                                                                             polyline]];
+    // A GeoJSON feature
+    NSDictionary *geoJSONFeature = [shapeCollectionFeature geoJSONDictionary];
+    
+    // it has the correct geometry
+    NSDictionary *expectedGeometry = @{@"type": @"GeometryCollection",
+                                       @"geometries": @[
+                                                         @{@"type": @"Point",
+                                                           @"coordinates": @[@(pointCoordinate.longitude), @(pointCoordinate.latitude)]},
+                                                         @{@"type": @"LineString",
+                                                           @"coordinates": @[@[@(coord1.longitude), @(coord1.latitude)],
+                                                                             @[@(coord2.longitude), @(coord2.latitude)]]}
+                                                       ]};
+    XCTAssertEqualObjects(geoJSONFeature[@"geometry"], expectedGeometry);
+}
+
 @end