Query map image sublayer

Find features in a sublayer based on attributes and location.

Use case

Sublayers of an ArcGISMapImageLayer may expose a ServiceFeatureTable through a table property. This allows you to perform the same queries available when working with a table from a FeatureLayer: attribute query, spatial query, statistics query, query for related features, etc. An image layer with a sublayer of counties can be queried by population to only show those above a minimum population.

How to use the sample

Specify a minimum population in the input field (values under 1810000 will produce a selection in all layers) and tap the “Query” button to query the sublayers in the current view extent. After a short time, the results for each sublayer will appear as graphics.

How it works

1. Create an ArcGISMapImageLayer object using the URL of an image service.
2. After loading the layer, get the sublayer you want to query from the map image layer’s mapImageSublayers array.
3. Load the sublayer, and then get its ServiceFeatureTable using ArcGISMapImageSublayer.table.
4. Create QueryParameters and define its whereClause and geometry.
5. Use FeatureTable.queryFeatures(using:) to get a FeatureQueryResult with features matching the query. The result is an enumerator of features.

Relevant API

• ArcGISMapImageLayer
• ArcGISMapImageSublayer
• FeatureQueryResult
• QueryParameters
• ServiceFeatureTable

About the data

The ArcGISMapImageLayer in the map uses the “USA” map service as its data source. This service is hosted by ArcGIS Online and is composed of four sublayers: “Cities”, “Highways”, “States”, and “Counties”. Since the cities, counties, and states tables all have a POP2000 field, they can all execute a query against that attribute and a map extent.

Tags

query, search