Hi, I notice that in 100.1 Release notes the LabelDefinition is a new function, and can only be created by using a Json,
but I don't know how to denfine the Json, Could you help to offer a sample Json for creating LabelDefinition?
There are a couple of examples in the Guide topic Label map features—ArcGIS Runtime SDK for .NET (WPF) | ArcGIS for Developers. Additionally the spec is covered in the Webmap spec doc (linked from the Guide topic above): labelingInfo | ArcGIS for Developers.
We do plan to add additional code samples to the public github repo demonstrating how to work with labels on features and graphics.