How to read files on an external drive plugged into the Lightning port

Is it possible to read files from myApp?

Yes. To do this, use the document picker API for your UI framework to request that the user choose a file. That’ll give you back a URL that you can then read and write like any other security-scoped URL.

For example, for UIKit you’d use the UIDocumentPickerViewController class.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

I'm now fearing that iOS cannot mount a FAT formatted storage device.

iOS can definitely mount FAT volumes over USB. Rather than testing with your app, I recommend that you test with the Files app. If the FAT volume doesn’t show up there, you know that it’s a problem with the mounting process rather than anything related to your code.

If it does turn out to be a problem with the mounting process, I recommend that you retest with a USB thumb drive. If that works and your camera fails, this issue is specific to the camera.

On the USB thumb drive front, you’ll need one of two configurations:

• An iPad with USB-C

• Any with Lightning and a Lightning to USB 3 Camera Adapter

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

is there anyway using any iOS device (like one with a USB-C) or any adapter/cable - so my app could also use PTP to retrieve files?

I don’t think so. PTP support is built in to the OS and AFAIK it has no API.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"