iOS发送UDP但Android手机无法接收UDP消息

Question

我使用AsyncUdpSocket在iphone中广播UDP消息，Android手机无法接收任何消息。发送以下UDP代码：

- (void)viewDidLoad {
[super viewDidLoad];

[self setupClientUdp];
}

- (void)setupClientUdp
{
 _clientUdp = [[AsyncUdpSocket alloc]initWithDelegate:self];
 NSError *err = nil;
 [_clientUdp enableBroadcast:YES error:&err];
 [self check:err];
 [_clientUdp bindToPort:9997 error:&err];
 [self check:err];
}
- (void)check:(NSError *)err
{
    NSLog(@"err=%@",err.domain);
}

 - (BOOL)onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData   *)data withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port
{
    return YES;
}

- (void)searchServer
{
    NSString *str = @"who is there?";
    NSData *data=[str dataUsingEncoding:NSUTF8StringEncoding];
    [_clientUdp sendData:data toHost:@"255.255.255.255" port:9998 withTimeout:-1 tag:0];
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    [self searchServer];
}

我写了一个iOS项目来接收iphone上的Udp消息，它可以接收UDP。UDP协议应该是平台无关的吗？或AsyncUdpSocket做不同的事情？