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When I plug in the "iPad (6th generation) Wi-Fi + Cellular" to the MacBook, it always says "unlock this iPad to use accessories." What it doesn't say is that it also won't charge until I do so. Took me several times to figure this out. (Has a cover, so I didn't see the message.)

But the iPhone 7+ doesn't do that. Both have IOS 12.4, so there must be a setting that I am not recognizing. Or are there distinct unlabeled "flavors" of IOS?

How can I make it start charging as soon as plugged in, even if screen is locked?

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  • Calling the MacBook an "accessory" is also a bit weird. – WGroleau Aug 27 '19 at 18:27
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The 'unlock to charge' is a new security feature since iOS 11.4. If you charge from a device that asks to communicate over USB you have to opt in. Alternatively, just plug in to a 'dumb' charger or employ a USB data block dongle / condom to physically prevent “juice jacking”. If there's no potential data connection, there's no restriction on charging or prompt to unlock.

To elaborate a bit, this design prevents hardware USB devices read data from your device. Remember when the FBI wanted to get into some guy's phone & tried to force Apple through the courts to 'let them in'? This is the current state of play in the hacker 'war'.

It can be disabled if you don't think you have any data on there worthy of government or black hat hacker intrusion.

Apple KB - Using USB accessories with iOS 11.4.1 and later

Settings > Face [Touch] ID & Passcode > USB Accessories

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  • If it’s an IOS feature, why did it never happen on the iPhone? And how does preventing charging protect the data? – WGroleau Aug 27 '19 at 23:57
  • It has even happened with a non-data USB charger built into an AC wall socket. – WGroleau Aug 28 '19 at 0:28
  • My iPad charges without any other action when plugged into a wallwart... @WGroleau and the cover can be closed or open... – Solar Mike Aug 28 '19 at 5:13
  • " If it’s an IOS feature, why did it never happen on the iPhone? And how does preventing charging protect the data? " @WGroleau You might not have seen this on your iPhone because it is running an older iOS that lacks this security feature. A well behaved USB device will draw only 100 mA before the host computer communicates with it and allows more power draw. Blocking all USB traffic prevents requests for more power. This protects the iPhone by not allowing any data transfer that might exploit a security flaw such as a buffer overflow. – MacGuffin Mar 5 at 8:27
  • " It has even happened with a non-data USB charger built into an AC wall socket. " @WGroleau USB chargers are getting "smarter" and may contain a microcontroller to negotiate power. This is not required for charging as specified by USB-BC & BrickID used by Apple for "dumb" chargers. Apple and others support "smart" charging by other protocols. E.g. PowerIQ chargers are claimed to identify the device plugged in to optimize charging, this would require some communication to tell the iPhone that it can provide 5V/2.4A of power as well as provide different volts and amps to different devices. – MacGuffin Mar 5 at 8:50

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