Sorry, but this is a feature that used to be part the app but is not any longer because it didn't work very well. We had way too many people running out of room on their devices and losing data.
You can upload directly from the iOS device to our site after the imagery has been transferred to the Files app using DJI Go. We maintain that the SD card is the best way to do things since you should be archiving all of the data you take anyway.
The Features page has been updated to reflect these changes. This feature was removed from all other sources of information about the app including the official app page and the App Store listings.