IOS BLE 连接参数设置失效

网上的文件的参数都不对，最新连接参数需要参考

https://developer.apple.com/accessories/Accessory-Design-Guidelines.pdf

其中关于连接参数描述如下： 

The accessory is responsible for the connection parameters used for the Low Energy connection. The
accessory should request connection parameters appropriate for its use case by sending an L2CAP
Connection Parameter Update Request at the appropriate time. See the Bluetooth 4.0 specification,
Volume 3, Part A, Section 4.20 for details.
The connection parameter request may be rejected if it does not meet the following guidelines:
● Peripheral Latency of up to 30 connection intervals.
● Supervision Timeout from 2 seconds to 6 seconds.
●Interval Min of at least 15 ms.
●Interval Min is a multiple of 15 ms.
● One of the following:
●Interval Max at least 15 ms greater than Interval Min.
●Interval Max and Interval Min both set to 15 ms.
●Interval Max * (Peripheral Latency + 1) of 2 seconds or less.
● Supervision Timeout greater than Interval Max * (Peripheral Latency + 1) * 3.
Note that if an accessory requests both an Interval Min and Interval Max of 15 ms, some devices will
scale the interval to 30 ms to balance power and performance constraints.
If Bluetooth Low Energy HID is one of the connected services of an accessory, a connection interval
down to 11.25 ms may be accepted by the device.
The device will not read or use the parameters in the Peripheral Preferred Connection Parameters
characteristic. See the Bluetooth 4.0 specification, Volume 3, Part C, Section 12.5.

按此设置来，即可，不然会拒绝。