How to connect and communicate iPhone/iPad to an External Camera by using External Accessory framework?

Hi, currently I have a project to develop a customized iOS/iPadOS app that is expected to can connect and communicate an External Cameras to iPhone/iPad device through USB Connection. The app should be able to access the taken photo from the External Cameras and/or take a shot executed by the app. The external camera manufacturers are like Canon, Nikon, and Sony.

As references, there are some apps that have that capability above released in Appstore:

  1. https://apps.apple.com/us/app/camera-connect-control/id1457548017
  2. https://apps.apple.com/id/app/image-capture-go/id1606632530?platform=iphone

As far as I know, I can connect to the Camera by using External Accessory framework provided by Apple as long the external device is MFi program supported and I have the detail of command protocol of the the device used.

In my case, Canon Camera is listed as MFi device in https://mfi.apple.com/account/accessory-search. But I don't have the detailed command protocol of the device to communicate with.

Questions:

  1. Is my understanding related External Accessory framework correct?
  2. How to connect and communicate external camera to iPhone/iPad via USB by using External Accessory framework?
  3. Is there any other work around to do the things like the reference apps in Appstore above?

Thank you very much.

How to connect and communicate iPhone/iPad to an External Camera by using External Accessory framework?
 
 
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