PingManager

支持同时进行多次 ping 操作，并大幅减少线程资源消耗

示例

用法

for host in hostArray{
   let ping = Ping()
   ping.delegate = self
   ping.host = host
   PingMannager.shared.add(ping)
}
PingMannager.shared.setup {
   PingMannager.shared.timeout = self.timeout
   PingMannager.shared.pingPeriod = self.period
   PingMannager.shared.startPing()
}