This sample shows how to add an instance of WMTSLayer. The WMTSLayer is used to create layers based on OGC Web Map Tile Service (WMTS). Typically, a WMTS service acts as a directory of WMTS layers, you can set a specific layer using the activeLayer property, (or else it will default to the first sublayer). The WMTSLayer initially executes a WMTS GetCapabilities request, which might require CORS or a proxy page.
The layers used in this sample are from Instituto Geográfico Nacional. Use the BasemapToggle widget to toggle between the layers.