https://developer.apple.com/documentation/swift/string/index(_:offsetby:)
index(_:offsetBy:) | Apple Developer Documentation
Returns an index that is the specified distance from the given index.
apple developerindexdocumentation
https://developers.arcgis.com/net/api-reference/api/net/Esri.ArcGISRuntime/Esri.ArcGISRuntime.Geometry.MapPointBuilder.OffsetBy.html
Method OffsetBy
Use ArcGIS Maps SDK for .NET to build powerful desktop and mobile apps that incorporate capabilities such as mapping, geocoding, routing, and geoprocessing.
method