来源：MacRumors https://goo.gl/1KDZV8
Source:iOS 11.4 Disables Lightning Connector After 7 Days, Limiting Law
Enforcement Access
(内文长，撷几个重点)
The iOS 11.4 update, currently being beta tested, includes a USB Restricted
Mode that introduces a week-long expiration date on access to the Lightning
port on your iOS devices if your phone hasn't been unlocked, which has
implications for law enforcement tools like the GrayKey box.
新的iOS11.4目前正在进行Beta测试，其中一项功能包括“若一个礼拜没有解锁装置，就会
上锁Lightning孔”，这项功能应该是为了阻止GrayKey box等法律性质工具强制破解手机。
In Elcomsoft's experience, after an iPhone or iPad has been updated to iOS
11.4, if it hasn't been unlocked or connected to a paired computer in the last 7
days using a passcode, the Lightning port is useless for data access and
limited to charging.
根据人员测试，更新iOS11.4的iPhone和iPad若在7天之内没有解锁或连接配对的电脑，
Lightning孔就会失去资料传输功能而仅能充电。
USB Restricted Mode won't prevent tools like the GrayKey box from being used
on an iPhone, but it does suggest that the passcode needs to be discovered
within a matter of days, severely limiting the amount of time that law
enforcement officials have to get into a device.
USB限制模式无法阻止GrayKey box等工具破解手机，但确定的是时间内必须被迫解，这
对法律用工具有极大的影响。
USB Restricted Mode was actually first introduced in the iOS 11.3 beta, but
it didn't make it into the iOS 11.3 release, so its presence in the iOS 11.4
beta does not guarantee that it will be included when iOS 11.4 launches to
the public.
其实USB限制模式在11.3beta版本中便出现过，但没有进入最后public版本，所以这项功能
在11.4 public版本并不保证会出现。