I have a new requirement for our apps to use external gps location updates (Bad Elf GPS Unit) besides the default Apple location service updates. I understood that I need to create a custom location display data source class that conforms to the protocol <AGSLocationDisplayDataSource> and replace the mapVidw.locationDisplay.dataSource. My question is that: how do I implement the start method in the protocol of <AGSLocationDisplayDataSource>? I'm currently still on 10.2.5 and later will look at the 100.2.1 as well. Can anyone please shed any light on this or have any working code to share? Many thanks for your help.