addPersistentStyleCustomLayer

Adds a new style custom layer.

Note: This is an experimental API and is a subject to change.

Whenever a new style is being parsed and currently used style has persistent layers, an engine will try to do following:

• keep the persistent layer at its relative position

• keep the source used by a persistent layer

• keep images added through addStyleImage method

In cases when a new style has the same layer, source or image resource, style's resources would be used instead and MapLoadingError event will be emitted.

Return

A string describing an error if the operation was not successful, or empty otherwise.

Parameters