GCDAsyncUdpSocket 發送廣播包時，出現Error receiving：error code ＝ 1

使用GCDAsyncUdpSocket，綁定IP，端口號，組播IP後，一切正常運行，真機調試，出現下面的錯誤。

Error receiving: Error Domain=GCDAsyncUdpSocketErrorDomain Code=1 "Must bind socket before you can receive data. You can do this explicitly via bind, or implicitly via connect or by sending data." UserInfo={NSLocalizedDescription=Must bind socket before you can receive data. You can do this explicitly via bind, or implicitly via connect or by sending data.}

檢查之後發現是手機不在內網，所以會出現這個錯誤。