MapplsHeatMap

MapplsHeatMap

MGLHeatmapStyleLayer

An MGLHeatmapStyleLayer is a style layer that renders a heatmap.

A heatmap visualizes the spatial distribution of a large, dense set of point data, using color to avoid cluttering the map with individual points at low zoom levels. The points are weighted by an attribute you specify. Use a heatmap style layer in conjunction with point or point collection features. These features can come from vector tiles loaded by an MGLVectorTileSource object, or they can be MGLPointAnnotation, MGLPointFeature, MGLPointCollection, or MGLPointCollectionFeature instances in an MGLShapeSource or MGLComputedShapeSource object.

Consider accompanying a heatmap style layer with an MGLCircleStyleLayer or MGLSymbolStyleLayer at high zoom levels. If you are unsure whether the point data in an MGLShapeSource is dense enough to warrant a heatmap, you can alternatively cluster the source using the MGLShapeSourceOptionClustered option and render the data using an MGLCircleStyleLayer or MGLSymbolStyleLayer.

You can access an existing heatmap style layer using the -[MGLStyle layerWithIdentifier:] method if you know its identifier; otherwise, find it using the MGLStyle.layers property. You can also create a new heatmap style layer and add it to the style using a method such as -[MGLStyle addLayer:].

See the Create a heatmap layer example to learn how to add this style layer to your map.

Example

let layer = MGLHeatmapStyleLayer(identifier: "earthquake-heat", source: earthquakes)
layer.heatmapWeight = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:(magnitude, 'linear', nil, %@)",
                                   [0: 0,
                                    6: 1])
layer.heatmapIntensity = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                                      [0: 1,
                                       9: 3])
mapView.style?.addLayer(layer)