Having trouble connecting to my iPad 2... Is the otg cable a good option..

Not always, for an iOS device.

Hi there, thank you for reaching DJI forum. As of the moment, ios device is not yet compatible using a n OTG cable for your Spark.  You can use OTG cable for Android devices by updating the firmware to the latest version. Thank you for your support.

I’m using OTG on my iPad Air 2 with no issues at all!

Fly safely
Alex

A quick "search" on this forum using OTG will provide you with a number of suggestions on the step-by-step process of connecting an OTG, both iOS and OTG.  In addition, make sure that your iPad is NOT running any other software in the background.  Close all apps FIRST before going into the start up routine.  In addition, I ALWAYS do a soft-clear of memory.  Hold down the "off" button until the  ShutDown Screen appears,... don't slide the shut-down slider, but instead, HOLD the Home button until the Home Screen re-appears.  This clears memory of any legacy code that may still be in memory.  Only takes a second and ensures your iPad is now dedicated to your Spark and Go4!  Ideally you will have turned off any Notifications and ensured that you iPad isn't trying to connect to your home wifi.  Many flyers forget to "undefault" their home wifi.  Then when their Spark disconnects (for whatever reason) the iPad tries to reconnect with home wifi.

I use it on an old unwanted iPhone.