FeatureCollectionLayer Class

Detailed Description

A feature collection layer is used to display the features in a feature collection. A feature collection provides a way of grouping logically-related, feature-collection tables. Tables in the collection can have different schema, geometry types, and rendering. A feature collection layer allows multiple tables with different schemas to be managed as a group.

Functional characteristics

Adding features to a map can help call attention to and describe things on that map. These features can contain points, lines, polygons, and associated text. (This capability is called Map Notes in ArcGIS Online.) Because they have different schema and geometry types, these features are stored in several distinct tables. A feature collection layer allows these tables to be rendered and managed as a group.

A feature collection can be saved in the map or as a stand-alone portal item. If you need to share the feature collection between several maps, it's best to store it as a separate portal item. If you need to make frequent (near real-time) edits to features in a collection, consider storing these in a feature service instead, because the feature collection is not refreshed until the map or portal item is reloaded. If features are used by a single map or are not subject to frequent updates, it might be best to store them directly in the map. Edits made to features stored in a map will be saved when the map is saved. Edits made to features stored in a portal item (and loaded into a map, for example) must be explicitly saved to the original portal item.

Performance characteristics

Feature collection layers are designed to display a moderate amount of feature data (hundreds or thousands of features). They are ideal for sharing static data (not subject to frequent updates) among several clients.

As full feature information is cached locally in a geodatabase and features are drawn natively, this layer type offers excellent display performance when zooming and panning the map, within the extent of cached features.

Downloading features to the device may require extensive network usage and local device storage space. After the features are present on the client, the app no longer needs to make requests for the data. App memory usage increases with the number and complexity of the features in the collection.

For samples, see:

• {https://developers.arcgis.com/qt/latest/cpp/sample-code/feature-collection-layer/} {Feature collection layer}
• {https://developers.arcgis.com/qt/latest/cpp/sample-code/feature-collection-layer-query/} {Feature collection layer (query)}