iOS websocket

iOS websocket

最近在开发一个直播应用，需要用到弹幕功能，后台说要用websocket来实现，所以学习了一下

一、 RocketSocket
搜索了一下发现，用的最多的还是Facebook的RocketSocket库，虽然已经停止维护了，但是还能使用。

1. 创建socket

   - (SRWebSocket *)webSocket {
       if (!_webSocket) {
           NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:SOCKET_SERVER_URL]];
           [request setValue:[NSString getAccessTokenString] forHTTPHeaderField:@"Authorization"];
           _webSocket = [[SRWebSocket alloc] initWithURLRequest:request];
           _webSocket.delegate = self;
       }
       return _webSocket;
   }
   

2. 打开socket，开始连接

   - (void)openWebSocket {
       if (self.webSocket.readyState == SR_OPEN) {
           return;
       }
       [self.webSocket open];
   }
   

3. 监听消息

   - (void)subscribeNewMessage {
       NSString *sendString = [NSString stringWithFormat:@"SUBSCRIBE
   destination: %@
   id: %@
   
   ", SOCKET_SEND_URL(@(self.channelId)), @"sub-0"];
       NSLog(@"%@", sendString);
       NSData *data = [sendString dataUsingEncoding:NSUTF8StringEncoding];
       [self.webSocket send:data];
   }
   

4. 发送消息

   - (void)sendMessage:(NSDictionary *)message {
       if (self.webSocket) {
           if (self.webSocket.readyState == SR_OPEN) {
               NSString *sendString = [NSString stringWithFormat:@"SEND
   Authorization: %@
   destination: %@
   
   %@", [NSString getAccessTokenString], SOCKET_SEND_URL(message[@"accountId"]), [NSString getJsonStringOfDictionary:message]];
               NSLog(@"sendMessage :%@", sendString);
               NSData *data = [sendString dataUsingEncoding:NSUTF8StringEncoding];
               [self.webSocket send:data];
           }
       } else {
           [self openWebSocket];
       }
   }
   

5. SRWebSocketDelegate, 代理事件

   #pragma mark - SRWebSocketDelegate
   
   - (void)webSocketDidOpen:(SRWebSocket *)webSocket {
       NSLog(@"webSocketDidOpen");
       if ([webSocket isEqual:self.webSocket]) {
           self.reopenCount = 0;
   //        [self startHeartBeat];
   //        [self subscribeNewMessage];
       }
   }
   
   - (void)webSocket:(SRWebSocket *)webSocket didFailWithError:(NSError *)error {
       NSLog(@"didFailWithError: %@", error);
       if ([webSocket isEqual:self.webSocket]) {
           [self reopenWebSocket];
       }
   }
   
   - (void)webSocket:(SRWebSocket *)webSocket didCloseWithCode:(NSInteger)code reason:(NSString *)reason wasClean:(BOOL)wasClean {
       NSLog(@"didCloseWithCode: %ld, %@, %d", (long)code, reason, wasClean);
       if ([webSocket isEqual:self.webSocket]) {
           [self closeWebSocket];
       }
   }
   
   - (void)webSocket:(SRWebSocket *)webSocket didReceivePong:(NSData *)pongPayload {
       NSLog(@"didReceivePong: %@", pongPayload);
       if ([webSocket isEqual:self.webSocket]) {
   
       }
   }
   
   - (void)webSocket:(SRWebSocket *)webSocket didReceiveMessage:(id)message {
       NSLog(@"didReceiveMessage: %@", message);
       if ([webSocket isEqual:self.webSocket]) {
           if (self.receiveMessage) {
               self.receiveMessage(message);
           }
       }
   }
   

6. 心跳和重连
   因为封装的比较简单，代码看起来很明了，但是有些地方需要自己完善。我这里主要加了心跳和重连机制。

   - (NSTimer *)heartBeatTimer {
       if (!_heartBeatTimer) {
           _heartBeatTimer = [NSTimer timerWithTimeInterval:heartBeatTimeInterval target:self selector:@selector(sendPing) userInfo:nil repeats:YES];
       }
       return _heartBeatTimer;
   }
   
   - (void)startHeartBeat {
       if (!_heartBeatTimer) {
           [[NSRunLoop currentRunLoop] addTimer:self.heartBeatTimer forMode:NSRunLoopCommonModes];
   //        [[NSRunLoop currentRunLoop] run];//子线程需要手动启动runloop
       }
   }
   
   - (void)stopHeartBeat {
       if (_heartBeatTimer) {
           [self.heartBeatTimer invalidate];
           self.heartBeatTimer = nil;
       }
   }
   
   - (void)sendPing {
       if (self.webSocket.readyState == SR_OPEN) {
           [self.webSocket sendPing:nil];
       }
   }
   

   - (void)reopenWebSocket {
       [self closeWebSocket];
       if (self.reopenCount >= maxReopenCount) {
           if (self.reconnectFailed) {
               self.reconnectFailed();
           }
           return;
       }
       dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 2 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
           [self openWebSocket];
           self.reopenCount ++;
       });
   }
   

二、 WebsocketStompKit
用rocketsocket写完之后，开始和后端联调，发现连接成功之后后端根本发现不了，连log都没有。对比着js中的方法，发现有用到Stomp，看源码挺简单的，只是把数据封装了一层，所以我就照着写了，在调试的时候还是不行。然后就去网上搜索iOS支持stomp协议的websocket库，就找到了这个WebsocketStompKit。

这个库封装的更好一些，用起来很方便。

1. 创建client

   - (STOMPClient *)webSocket {
       if (!_webSocket) {
           NSURL *url = [NSURL URLWithString:SOCKET_SERVER_URL];
           NSDictionary *headers = @{
               @"Authorization": [NSString getAccessTokenString],
           };
           _webSocket = [[STOMPClient alloc] initWithURL:url webSocketHeaders:headers useHeartbeat:YES];
           _webSocket.delegate = self;
       }
       return _webSocket;
   }
   

2. 打开socket，开始连接

   - (void)openWebSocket {
       NSDictionary *headers = @{
           @"Authorization": [NSString getAccessTokenString],
       };
       [self.webSocket connectWithHeaders:headers completionHandler:^(STOMPFrame *connectedFrame, NSError *error) {
           NSLog(@"connectWithHeaders: %@---%@", connectedFrame, error);
           if (error) {//连接失败提示
               dispatch_async(dispatch_get_main_queue(), ^{
                   
               });
           } else {//连接成功订阅消息
               [self subscribeNewMessage];
           }
       }];
   }
   

3. 订阅消息

   - (void)subscribeNewMessage {
       [self.webSocket subscribeTo:[NSString stringWithFormat:@"/topic/222.%lld", self.channelId] headers:@{} messageHandler:^(STOMPMessage *message) {
           NSLog(@"receive message: %@", message);
           if (self.receiveMessage) {
               self.receiveMessage([NSString getDictionaryFromJsonString:message.body]);
           }
       }];
   }
   

4. 发送消息

   - (void)sendMessage:(NSDictionary *)message {
       NSDictionary *headers = @{
           @"Authorization": [NSString getAccessTokenString],
       };
       [self.webSocket sendTo:SOCKET_SEND_URL(message[@"accountId"]) headers:headers body:[NSString getJsonStringOfDictionary:message]];
   }
   

使用过程中又崩溃的情况，我这里修改了几个地方，详情请见我的Fork

比较上面的两种库，回调方式分别用来delegate和block，看起来使用delegate的方式容易对整个流程有把控，每一步都有对应的方法，写起来稍微麻烦一些，但是容易理解；使用block的方式写起来很简单，但是理解起来稍显困难，不过更容易集中注意力到事件及回调上，其他过程可忽略。我倾向于前者。

参考:
iOS WebSocket长连接
WebSocket Demo
WebsocketStompKit使用