iOS WebSocket长链接的实现方法

WebSocket

WebSocket 是 HTML5 一种新的协议。它实现了浏览器与服务器全双工通信，能更好的节省服务器资源和带宽并达到实时通讯，它建立在 TCP 之上，同 HTTP 一样通过 TCP 来传输数据，但是它和 HTTP 最大不同是：WebSocket 是一种双向通信协议.

由于项目需要创建一个聊天室,需要通过长链接,和后台保持通讯,进行聊天,并且实时进行热点消息的推送.

目前Facebook的SocketRocket应该是目前最好的关于SocketRocket使用的框架了.而且简单易用.

使用

一般一个项目在启动后的某个时机会启动创建一个长链接,如果需要多个就多次创建.如果只要一个就可以封装为一个单例,全局使用.

可以使用podpod管理库, 在podfile中加入

pod 'SocketRocket'

在使用命令行工具cd到当前工程 安装

pod install

导入头文件后即可使用.

为求稳定,我的做法是copy的FaceBook里SocketRocket库到项目里. --> SocketRocket地址

1.首先创建一个名为 WebSocketManager 的单例类,

+(instancetype)shared;

2.创建一个枚举,分别表示WebSocket的链接状态

typedef NS_ENUM(NSUInteger,WebSocketConnectType){
  WebSocketDefault = 0,  //初始状态,未连接,不需要重新连接
  WebSocketConnect,    //已连接
  WebSocketDisconnect  //连接后断开,需要重新连接
};

3.创建连接

//建立长连接
- (void)connectServer;

4.处理连接成功的结果;

-(void)webSocketDidOpen:(RMWebSocket *)webSocket; //连接成功回调

5.处理连接失败的结果

- (void)webSocket:(SRWebSocket *)webSocket didFailWithError:(NSError *)error;//连接失败回调

6.接收消息

///接收消息回调,需要提前和后台约定好消息格式.
- (void)webSocket:(SRWebSocket *)webSocket didReceiveMessageWithString:(nonnull NSString *)string

7.关闭连接

- (void)webSocket:(SRWebSocket *)webSocket didCloseWithCode:(NSInteger)code reason:(NSString *)reason wasClean:(BOOL)wasClean;///关闭连接回调的代理

8.为保持长链接的连接状态,需要定时向后台发送消息,就是俗称的:心跳包.

需要创建一个定时器,固定时间发送消息.

9.链接断开情况处理:

首先判断是否是主动断开,如果是主动断开就不作处理.

如果不是主动断开链接,需要做重新连接的逻辑.

具体代码如下:

WebSocketManager.h 中的代码

#import
<foundation foundation="" h="">

#import "RMWebSocket.h"
typedef NS_ENUM(NSUInteger,WebSocketConnectType){
  WebSocketDefault = 0, //初始状态,未连接
  WebSocketConnect,   //已连接
  WebSocketDisconnect  //连接后断开
};
@class WebSocketManager;
@protocol WebSocketManagerDelegate
 <nsobject>

- (void)webSocketManagerDidReceiveMessageWithString:(NSString *)string;
@end
NS_ASSUME_NONNULL_BEGIN
@interface WebSocketManager : NSObject
@property (nonatomic, strong) RMWebSocket *webSocket;
@property(nonatomic,weak) id
 <websocketmanagerdelegate nbsp="">
  delegate;
@property (nonatomic, assign)  BOOL isConnect; //是否连接
@property (nonatomic, assign)  WebSocketConnectType connectType;
+(instancetype)shared;
- (void)connectServer;//建立长连接
- (void)reConnectServer;//重新连接
- (void)RMWebSocketClose;//关闭长连接
- (void)sendDataToServer:(NSString *)data;//发送数据给服务器
@end
NS_ASSUME_NONNULL_END
 </websocketmanagerdelegate>
 </nsobject>
</foundation>

WebSocketManager.m 中的代码

#import "WebSocketManager.h"
@interface WebSocketManager ()
<rmwebsocketdelegate>

@property (nonatomic, strong) NSTimer *heartBeatTimer; //心跳定时器
@property (nonatomic, strong) NSTimer *netWorkTestingTimer; //没有网络的时候检测网络定时器
@property (nonatomic, assign) NSTimeInterval reConnectTime; //重连时间
@property (nonatomic, strong) NSMutableArray *sendDataArray; //存储要发送给服务端的数据
@property (nonatomic, assign) BOOL isActivelyClose;  //用于判断是否主动关闭长连接，如果是主动断开连接，连接失败的代理中，就不用执行 重新连接方法
@end
@implementation WebSocketManager
+(instancetype)shared{
  static WebSocketManager *_instance = nil;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    _instance = [[self alloc]init];
  });
  return _instance;
}
- (instancetype)init
{
  self = [super init];
  if(self){
    self.reConnectTime = 0;
    self.isActivelyClose = NO;

    self.sendDataArray = [[NSMutableArray alloc] init];
  }
  return self;
}
//建立长连接
- (void)connectServer{
  self.isActivelyClose = NO;

  self.webSocket.delegate = nil;
  [self.webSocket close];
  _webSocket = nil;
//  self.webSocket = [[RMWebSocket alloc] initWithURL:[NSURL URLWithString:@"https://dev-im-gateway.runxsports.com/ws/token=88888888"]];
  self.webSocket = [[RMWebSocket alloc] initWithURL:[NSURL URLWithString:@"ws://chat.workerman.net:7272"]];
  self.webSocket.delegate = self;
  [self.webSocket open];
}
- (void)sendPing:(id)sender{
  [self.webSocket sendPing:nil error:NULL];
}
#pragma mark --------------------------------------------------
#pragma mark - socket delegate
///开始连接
-(void)webSocketDidOpen:(RMWebSocket *)webSocket{

  NSLog(@"socket 开始连接");
  self.isConnect = YES;
  self.connectType = WebSocketConnect;
  [self initHeartBeat];///开始心跳

}
///连接失败
-(void)webSocket:(RMWebSocket *)webSocket didFailWithError:(NSError *)error{
  NSLog(@"连接失败");
  self.isConnect = NO;
  self.connectType = WebSocketDisconnect;
  DLog(@"连接失败，这里可以实现掉线自动重连，要注意以下几点");
  DLog(@"1.判断当前网络环境，如果断网了就不要连了，等待网络到来，在发起重连");
  DLog(@"3.连接次数限制，如果连接失败了，重试10次左右就可以了");

  //判断网络环境
  if (AFNetworkReachabilityManager.sharedManager.networkReachabilityStatus == AFNetworkReachabilityStatusNotReachable){ //没有网络

    [self noNetWorkStartTestingTimer];//开启网络检测定时器
  }else{ //有网络

    [self reConnectServer];//连接失败就重连
  }
}
///接收消息
-(void)webSocket:(RMWebSocket *)webSocket didReceiveMessageWithString:(NSString *)string{

  NSLog(@"接收消息---- %@",string);
  if ([self.delegate respondsToSelector:@selector(webSocketManagerDidReceiveMessageWithString:)]) {
    [self.delegate webSocketManagerDidReceiveMessageWithString:string];
  }
}
///关闭连接
-(void)webSocket:(RMWebSocket *)webSocket didCloseWithCode:(NSInteger)code reason:(NSString *)reason wasClean:(BOOL)wasClean{

  self.isConnect = NO;
  if(self.isActivelyClose){
    self.connectType = WebSocketDefault;
    return;
  }else{
    self.connectType = WebSocketDisconnect;
  }

  DLog(@"被关闭连接，code:%ld,reason:%@,wasClean:%d",code,reason,wasClean);

  [self destoryHeartBeat]; //断开连接时销毁心跳

  //判断网络环境
  if (AFNetworkReachabilityManager.sharedManager.networkReachabilityStatus == AFNetworkReachabilityStatusNotReachable){ //没有网络
    [self noNetWorkStartTestingTimer];//开启网络检测
  }else{ //有网络
    NSLog(@"关闭连接");
    _webSocket = nil;
    [self reConnectServer];//连接失败就重连
  }
}
///ping
-(void)webSocket:(RMWebSocket *)webSocket didReceivePong:(NSData *)pongData{
  NSLog(@"接受pong数据--> %@",pongData);
}
#pragma mark - NSTimer
//初始化心跳
- (void)initHeartBeat{
  //心跳没有被关闭
  if(self.heartBeatTimer) {
    return;
  }
  [self destoryHeartBeat];
  dispatch_main_async_safe(^{
    self.heartBeatTimer = [NSTimer timerWithTimeInterval:10 target:self selector:@selector(senderheartBeat) userInfo:nil repeats:true];
    [[NSRunLoop currentRunLoop]addTimer:self.heartBeatTimer forMode:NSRunLoopCommonModes];
  })

}
//重新连接
- (void)reConnectServer{
  if(self.webSocket.readyState == RM_OPEN){
    return;
  }

  if(self.reConnectTime > 1024){ //重连10次 2^10 = 1024
    self.reConnectTime = 0;
    return;
  }

  WS(weakSelf);
  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(self.reConnectTime *NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

    if(weakSelf.webSocket.readyState == RM_OPEN && weakSelf.webSocket.readyState == RM_CONNECTING) {
      return;
    }

    [weakSelf connectServer];
    //    CTHLog(@"正在重连......");

    if(weakSelf.reConnectTime == 0){ //重连时间2的指数级增长
      weakSelf.reConnectTime = 2;
    }else{
      weakSelf.reConnectTime *= 2;
    }
  });

}
//发送心跳
- (void)senderheartBeat{
  //和服务端约定好发送什么作为心跳标识，尽可能的减小心跳包大小
  WS(weakSelf);
  dispatch_main_async_safe(^{
    if(weakSelf.webSocket.readyState == RM_OPEN){
      [weakSelf sendPing:nil];
    }
  });
}
//没有网络的时候开始定时 -- 用于网络检测
- (void)noNetWorkStartTestingTimer{
  WS(weakSelf);
  dispatch_main_async_safe(^{
    weakSelf.netWorkTestingTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:weakSelf selector:@selector(noNetWorkStartTesting) userInfo:nil repeats:YES];
    [[NSRunLoop currentRunLoop] addTimer:weakSelf.netWorkTestingTimer forMode:NSDefaultRunLoopMode];
  });
}
//定时检测网络
- (void)noNetWorkStartTesting{
  //有网络
  if(AFNetworkReachabilityManager.sharedManager.networkReachabilityStatus != AFNetworkReachabilityStatusNotReachable)
  {
    //关闭网络检测定时器
    [self destoryNetWorkStartTesting];
    //开始重连
    [self reConnectServer];
  }
}
//取消网络检测
- (void)destoryNetWorkStartTesting{
  WS(weakSelf);
  dispatch_main_async_safe(^{
    if(weakSelf.netWorkTestingTimer)
    {
      [weakSelf.netWorkTestingTimer invalidate];
      weakSelf.netWorkTestingTimer = nil;
    }
  });
}
//取消心跳
- (void)destoryHeartBeat{
  WS(weakSelf);
  dispatch_main_async_safe(^{
    if(weakSelf.heartBeatTimer)
    {
      [weakSelf.heartBeatTimer invalidate];
      weakSelf.heartBeatTimer = nil;
    }
  });
}
//关闭长连接
- (void)RMWebSocketClose{
  self.isActivelyClose = YES;
  self.isConnect = NO;
  self.connectType = WebSocketDefault;
  if(self.webSocket)
  {
    [self.webSocket close];
    _webSocket = nil;
  }

  //关闭心跳定时器
  [self destoryHeartBeat];

  //关闭网络检测定时器
  [self destoryNetWorkStartTesting];
}
//发送数据给服务器
- (void)sendDataToServer:(NSString *)data{
  [self.sendDataArray addObject:data];

  //[_webSocket sendString:data error:NULL];

  //没有网络
  if (AFNetworkReachabilityManager.sharedManager.networkReachabilityStatus == AFNetworkReachabilityStatusNotReachable)
  {
    //开启网络检测定时器
    [self noNetWorkStartTestingTimer];
  }
  else //有网络
  {
    if(self.webSocket != nil)
    {
      // 只有长连接OPEN开启状态才能调 send 方法，不然会Crash
      if(self.webSocket.readyState == RM_OPEN)
      {
//        if (self.sendDataArray.count > 0)
//        {
//          NSString *data = self.sendDataArray[0];
          [_webSocket sendString:data error:NULL]; //发送数据
//          [self.sendDataArray removeObjectAtIndex:0];
//
//        }
      }
      else if (self.webSocket.readyState == RM_CONNECTING) //正在连接
      {
        DLog(@"正在连接中，重连后会去自动同步数据");
      }
      else if (self.webSocket.readyState == RM_CLOSING || self.webSocket.readyState == RM_CLOSED) //断开连接
      {
        //调用 reConnectServer 方法重连,连接成功后 继续发送数据
        [self reConnectServer];
      }
    }
    else
    {
      [self connectServer]; //连接服务器
    }
  }
}
@end
</rmwebsocketdelegate>

注意点

我们在发送消息之前,也就是调用  senderheartBeat/ sendDataToServer:方法之前，一定要判断当前scoket是否连接，如果不是连接状态，程序则会crash。

iOS手机屏幕息屏或者回主页的时候有可能会造成链接断开,我这边的处理是在回到屏幕的时候,判断状态,如果已经断开,就重新连接.

在 AppDelegate 中:

- (void)applicationDidBecomeActive:(UIApplication *)application {
  // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
  if ([WebSocketManager shared].connectType == WebSocketDisconnect) {
    [[WebSocketManager shared] connectServer];
  }
}

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