iOS 蓝牙连接 connectionSupervisionTimeout 是720ms 还是 2~6s这里720ms是iPhone作为主设connect时设定的connectionParameter,但是蓝牙协议允许外设来根据实际情况协商 connection Supervision Timeout以满足需求,故《 Accessory Design Guidelines for Apple Devices 》文档在此时约束了外设协商的 Supervision Timeout from 2 seconds to 6 seconds.