iPhone - User gets the message that the accessory draws too much power.

We suggest you always turn on your camera before connecting it to the phone. If you forget and you connect it while turned off, you can unplug it, turn it on and plug it in again.

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UPDATE


This is happening because in some cameras the USB connectivity setting is set to draw power from the connected USB device and because most of the devices so far had enough power in the battery to handle the cameras, this issue was not obvious. However this is not the case with iPhones since their battery capacity is less than iPad or laptops.
Before creating a support ticket please make sure that you have changed your USB settings to not draw power from the connect device.