In message 
          mm0fmf  wrote:

>On 01/02/2019 03:04, bob prohaska wrote:
>> When I plug an iPad into my Pi3 both devices seem to
>> notice the connection, but an attempt to access the
>> iPad from Raspbian results in
>> Error Failed to get folder list: -1 Unspecified error
>>
>> The Pi seems to think the iPad is a camers, which is a
>> good start.
>>
>> The iPad asks "Allow this device to access photos and
>> videos?", to which I touch Allow. No error is reported.
>>
>> Is a useful connection possible?
>>
>I'm not an Apple user but I think you will find iPads, iPhones support a
>proprietary protocol and I don't know if drivers for Linux are available
>to handle transfers to and from them.

It's some years ago that I tried... I expected the same as you, but
was surprised that the iPhone supported MTP in what seemes a perfectly
standard way.

Android phones, when plugged in, default to charge only.  You have to
change the setting, every time you plug in, if you want to exchange
files via MTP.  It's a simple security mechanism.  I would expect
iDevices to do something similar, for the same reason.

Dave

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