Line Provider
Line Providers are components that are responsible for taking the Line objects that the Dialogue Runner produces, and fetches the appropriate localised content for that line. Line Providers produce LocalizedLine objects, which are sent to the Dialogue Runner's Dialogue Views.
When a Yarn script runs, the Dialogue Runner produces Line objects. These objects contain information about the line, but not the text of the line itself. This is because it's the responsibility of the game to load the user-facing parts of the line, including the text of the line in the player's current language setting, as well as any other assets that may be needed to present the line (such as audio files for voiceover.)
Yarn Spinner comes with three built-in types of line providers:
Text Line Provider is a Line Provider that fetches the text of a line, given a language to use.
Audio Line Provider is a Line Provider that fetches the text of a line as well as an Audio Clip, given languages to use.
Unity Localised Line provider is a Line Provider that fetches the text and any localised assets from Unity's Localization system.
If you don't set up a Line Provider for a Dialogue Runner, it will automatically create a Text Line Provider, and configure it to use the user's current language.