Apple map public transit route

Hi,

I'm developing an app where I need to draw public route polylines on map. I can draw .automobile polylines, but when I chose .transit, it won't show anything on the map.

I'm wondering how I can get a public transit route and estimate time as a JSON file and draw a route on a map?

How apple map does show very clear and nice step by step routes?

Thank you,
Apple map public transit route
 
 
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