data 转换 中文
NSStringEncoding strEncode = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
NSString *strReceive = [[NSString alloc] initWithData:receivedData encoding:strEncode];
NSStringEncoding strEncode = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
NSString *strReceive = [[NSString alloc] initWithData:receivedData encoding:strEncode];