一、說明

2017年4月份公司瞻赶，在做海外直播產(chǎn)品的時候赛糟，客戶端需要實(shí)時顯示些交互信息 ，剛開始由于產(chǎn)品處于驗(yàn)證階段用戶量少砸逊，就采用了輪尋的方式璧南，每間隔15s（當(dāng)然這也不及時），去服務(wù)器拉取一下信息师逸。由于運(yùn)營速度的加快司倚，用戶量很快就上來了，導(dǎo)致，服務(wù)器在高峰時段对湃，資源被占滿而無法響應(yīng)崖叫。和服務(wù)端小伙伴商議后迅速采用遗淳，長連接的方式拍柒，來處理客戶端和服務(wù)端不定時頻繁發(fā)消息的業(yè)務(wù)。然后屈暗，在網(wǎng)上就找到了Facebook的SRWebSocket框架拆讯，更多信息參考 https://github.com/facebook/SocketRocket

二 、用法

1养叛、 實(shí)現(xiàn)的功能

1.webSocket    ---   開啟長連接
2.webSocket    ---   關(guān)閉長連接
3.webSocket    ---   長連接連接失敗种呐，自動重連（連接10次）
4.webSocket    ---   無網(wǎng)的時候網(wǎng)絡(luò)檢測（此時會停止心跳），有網(wǎng)的時候弃甥，自動重連
5.webSocket    ---   和服務(wù)端建立連接后發(fā)送心跳
6.webSocket    ---   給服務(wù)端發(fā)送數(shù)據(jù)
7.webSocket    ---   接收服務(wù)端數(shù)據(jù)

2爽室、以下是封裝 SRWebSocket 的代碼

#import <Foundation/Foundation.h>
#import "SRWebSocket.h"
@interface WebSocketManager : NSObject

@property (nonatomic, strong) SRWebSocket *webSocket;
+ (instancetype)sharedSocketManager;//單例
- (void)connectServer;//建立長連接
- (void)SRWebSocketClose;//關(guān)閉長連接
- (void)sendDataToServer:(id)data;//發(fā)送數(shù)據(jù)給服務(wù)器
@end

主線程異步隊(duì)列
#define dispatch_main_async_safe(block)\
if ([NSThread isMainThread]) {\
block();\
} else {\
dispatch_async(dispatch_get_main_queue(), block);\
}


#import "WebSocketManager.h"

@interface WebSocketManager()<SRWebSocketDelegate>

@property (nonatomic, strong) NSTimer *heartBeatTimer; //心跳定時器
@property (nonatomic, strong) NSTimer *netWorkTestingTimer; //沒有網(wǎng)絡(luò)的時候檢測網(wǎng)絡(luò)定時器
@property (nonatomic, strong) dispatch_queue_t queue; //數(shù)據(jù)請求隊(duì)列（串行隊(duì)列）
@property (nonatomic, assign) NSTimeInterval reConnectTime; //重連時間
@property (nonatomic, strong) NSMutableArray *sendDataArray; //存儲要發(fā)送給服務(wù)端的數(shù)據(jù)
@property (nonatomic, assign) BOOL isActivelyClose;    //用于判斷是否主動關(guān)閉長連接，如果是主動斷開連接淆攻，連接失敗的代理中阔墩，就不用執(zhí)行 重新連接方法

@end

@implementation WebSocketManager

//單例
+ (instancetype)sharedSocketManager
{
    static WebSocketManager *_instace = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken,^{
        _instace = [[self alloc] init];
    });
    return _instace;
}

- (instancetype)init
{
    self = [super init];
    if(self)
    {
        self.reConnectTime = 0;
        self.isActivelyClose = NO;
        self.queue = dispatch_queue_create("BF",NULL);
        self.sendDataArray = [[NSMutableArray alloc] init];
    }
    return self;
}

#pragma mark - NSTimer

//初始化心跳
- (void)initHeartBeat
{
    //心跳沒有被關(guān)閉
    if(self.heartBeatTimer)
    {
        return;
    }
    
    [self destoryHeartBeat];
    
    WS(weakSelf);
    dispatch_main_async_safe(^{
        weakSelf.heartBeatTimer  = [NSTimer timerWithTimeInterval:10 target:weakSelf selector:@selector(senderheartBeat) userInfo:nil repeats:true];
        [[NSRunLoop currentRunLoop]addTimer:weakSelf.heartBeatTimer forMode:NSRunLoopCommonModes];
    });
}

//取消心跳
- (void)destoryHeartBeat
{
    WS(weakSelf);
    dispatch_main_async_safe(^{
        if(weakSelf.heartBeatTimer)
        {
            [weakSelf.heartBeatTimer invalidate];
            weakSelf.heartBeatTimer = nil;
        }
    });
}

//沒有網(wǎng)絡(luò)的時候開始定時 -- 用于網(wǎng)絡(luò)檢測
- (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];
    });
}

//取消網(wǎng)絡(luò)檢測
- (void)destoryNetWorkStartTesting
{
    WS(weakSelf);
    dispatch_main_async_safe(^{
        if(weakSelf.netWorkTestingTimer)
        {
            [weakSelf.netWorkTestingTimer invalidate];
            weakSelf.netWorkTestingTimer = nil;
        }
    });
}

#pragma mark - private -- webSocket相關(guān)方法

//發(fā)送心跳
- (void)senderheartBeat
{
    //和服務(wù)端約定好發(fā)送什么作為心跳標(biāo)識，盡可能的減小心跳包大小
    WS(weakSelf);
    dispatch_main_async_safe(^{
        if(weakSelf.webSocket.readyState == SR_OPEN)
        {
            [weakSelf.webSocket sendPing:nil];
        }
    });
}

//定時檢測網(wǎng)絡(luò)
- (void)noNetWorkStartTesting
{
    //有網(wǎng)絡(luò)
    if(AFNetworkReachabilityManager.sharedManager.networkReachabilityStatus != AFNetworkReachabilityStatusNotReachable)
    {
        //關(guān)閉網(wǎng)絡(luò)檢測定時器
        [self destoryNetWorkStartTesting];
        //開始重連
        [self reConnectServer];
    }
}

//建立長連接
- (void)connectServer
{
    self.isActivelyClose = NO;
    
    if(self.webSocket)
    {
        self.webSocket = nil;
    }
    
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"ws://ip地址:端口號"]];
    self.webSocket = [[SRWebSocket alloc] initWithURLRequest:request];
    self.webSocket.delegate = self;
    [self.webSocket open];
}

//重新連接服務(wù)器
- (void)reConnectServer
{
    if(self.webSocket.readyState == SR_OPEN)
    {
        return;
    }
    
    if(self.reConnectTime > 1024)  //重連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 == SR_OPEN && weakSelf.webSocket.readyState == SR_CONNECTING)
        {
            return;
        }
        
        [weakSelf connectServer];
        CTHLog(@"正在重連......");
        
        if(weakSelf.reConnectTime == 0)  //重連時間2的指數(shù)級增長
        {
            weakSelf.reConnectTime = 2;
        }
        else
        {
            weakSelf.reConnectTime *= 2;
        }
    });
    
}

//關(guān)閉連接
- (void)SRWebSocketClose;
{
    self.isActivelyClose = YES;
    [self webSocketClose];
    
    //關(guān)閉心跳定時器
    [self destoryHeartBeat];
    
    //關(guān)閉網(wǎng)絡(luò)檢測定時器
    [self destoryNetWorkStartTesting];
}

//關(guān)閉連接
- (void)webSocketClose
{
    if(self.webSocket)
    {
        [self.webSocket close];
        self.webSocket = nil;
    }
}

//發(fā)送數(shù)據(jù)給服務(wù)器
- (void)sendDataToServer:(id)data
{
    [self.sendDataArray addObject:data];
    [self sendeDataToServer];
}


- (void)sendeDataToServer
{
    WS(weakSelf);
    
    //把數(shù)據(jù)放到一個請求隊(duì)列中
    dispatch_async(self.queue, ^{
        
        //沒有網(wǎng)絡(luò)
        if (AFNetworkReachabilityManager.sharedManager.networkReachabilityStatus == AFNetworkReachabilityStatusNotReachable)
        {
            //開啟網(wǎng)絡(luò)檢測定時器
            [weakSelf noNetWorkStartTestingTimer];
        }
        else //有網(wǎng)絡(luò)
        {
            if(weakSelf.webSocket != nil)
            {
                // 只有長連接OPEN開啟狀態(tài)才能調(diào) send 方法瓶珊，不然會Crash
                if(weakSelf.webSocket.readyState == SR_OPEN)
                {
                    if (weakSelf.sendDataArray.count > 0)
                    {
                        NSString *data = weakSelf.sendDataArray[0];
                        [weakSelf.webSocket send:data]; //發(fā)送數(shù)據(jù)
                        [weakSelf.sendDataArray removeObjectAtIndex:0];
       
                        if([weakSelf.sendDataArray count] > 0)
                        {
                            [weakSelf sendeDataToServer];
                        }
                    }
                }
                else if (weakSelf.webSocket.readyState == SR_CONNECTING) //正在連接
                {
                    CTHLog(@"正在連接中啸箫，重連后會去自動同步數(shù)據(jù)");
                }
                else if (weakSelf.webSocket.readyState == SR_CLOSING || weakSelf.webSocket.readyState == SR_CLOSED) //斷開連接
                {
                    //調(diào)用 reConnectServer 方法重連,連接成功后 繼續(xù)發(fā)送數(shù)據(jù)
                    [weakSelf reConnectServer];
                }
            }
            else
            {
                [weakSelf connectServer]; //連接服務(wù)器
            }
        }
    });
}

#pragma mark - SRWebSocketDelegate -- webSockect代理

//連接成功回調(diào)
- (void)webSocketDidOpen:(SRWebSocket *)webSocket
{
    CTHLog(@"webSocket ===  連接成功");
    
    [self initHeartBeat]; //開啟心跳
    
    //如果有尚未發(fā)送的數(shù)據(jù)，繼續(xù)向服務(wù)端發(fā)送數(shù)據(jù)
    if ([self.sendDataArray count] > 0){
        [self sendeDataToServer];
    }
}

//連接失敗回調(diào)
- (void)webSocket:(SRWebSocket *)webSocket didFailWithError:(NSError *)error
{
    //用戶主動斷開連接伞芹，就不去進(jìn)行重連
    if(self.isActivelyClose)
    {
        return;
    }
    
    [self destoryHeartBeat]; //斷開連接時銷毀心跳
    
    CTHLog(@"連接失敗忘苛，這里可以實(shí)現(xiàn)掉線自動重連，要注意以下幾點(diǎn)");
    CTHLog(@"1.判斷當(dāng)前網(wǎng)絡(luò)環(huán)境唱较，如果斷網(wǎng)了就不要連了扎唾，等待網(wǎng)絡(luò)到來，在發(fā)起重連");
    CTHLog(@"3.連接次數(shù)限制南缓，如果連接失敗了稽屏，重試10次左右就可以了");
    
    //判斷網(wǎng)絡(luò)環(huán)境
    if (AFNetworkReachabilityManager.sharedManager.networkReachabilityStatus == AFNetworkReachabilityStatusNotReachable) //沒有網(wǎng)絡(luò)
    {
        [self noNetWorkStartTestingTimer];//開啟網(wǎng)絡(luò)檢測定時器
    }
    else //有網(wǎng)絡(luò)
    {
        [self reConnectServer];//連接失敗就重連
    }
}

//連接關(guān)閉,注意連接關(guān)閉不是連接斷開，關(guān)閉是 [socket close] 客戶端主動關(guān)閉西乖，斷開可能是斷網(wǎng)了狐榔，被動斷開的。
- (void)webSocket:(SRWebSocket *)webSocket didCloseWithCode:(NSInteger)code reason:(NSString *)reason wasClean:(BOOL)wasClean
{
    // 在這里判斷 webSocket 的狀態(tài) 是否為 open , 大家估計會有些奇怪 获雕，因?yàn)槲覀兊姆?wù)器都在海外薄腻，會有些時間差，經(jīng)過測試届案，我們在進(jìn)行某次連接的時候庵楷，上次重連的回調(diào)剛好回來，而本次重連又成功了，就會誤以為尽纽，本次沒有重連成功咐蚯，而再次進(jìn)行重連，就會出現(xiàn)問題弄贿，所以在這里做了一下判斷
    if(self.webSocket.readyState == SR_OPEN || self.isActivelyClose)
    {
        return;
    }
    
    CTHLog(@"被關(guān)閉連接春锋，code:%ld,reason:%@,wasClean:%d",code,reason,wasClean);
    
    [self destoryHeartBeat]; //斷開連接時銷毀心跳
    
    //判斷網(wǎng)絡(luò)環(huán)境
    if (AFNetworkReachabilityManager.sharedManager.networkReachabilityStatus == AFNetworkReachabilityStatusNotReachable) //沒有網(wǎng)絡(luò)
    {
        [self noNetWorkStartTestingTimer];//開啟網(wǎng)絡(luò)檢測
    }
    else //有網(wǎng)絡(luò)
    {
        [self reConnectServer];//連接失敗就重連
    }
}

//該函數(shù)是接收服務(wù)器發(fā)送的pong消息，其中最后一個參數(shù)是接受pong消息的
-(void)webSocket:(SRWebSocket *)webSocket didReceivePong:(NSData*)pongPayload
{
    NSString* reply = [[NSString alloc] initWithData:pongPayload encoding:NSUTF8StringEncoding];
    CTHLog(@"reply === 收到后臺心跳回復(fù) Data:%@",reply);
}

//收到服務(wù)器發(fā)來的數(shù)據(jù)
- (void)webSocket:(SRWebSocket *)webSocket didReceiveMessage:(id)message
{
    NSMutableDictionary *dataDic = [NSMutableDictionary dictionaryWithJsonString:message];
    
    /*根據(jù)具體的業(yè)務(wù)做具體的處理*/
}

@end

三差凹、注意事項(xiàng)

1期奔、每次重連接的時候需要重新建立連接通道
2、由于按home鍵APP進(jìn)入后臺危尿，仍然要保持長連接通道不被系統(tǒng)立即斷掉呐萌，需要在 AppDelegate 中做以下處理，向系統(tǒng)申請資源谊娇，不過這個資源申請也是有限的肺孤，最多只有 10分鐘。也可以實(shí)現(xiàn)無限后臺機(jī)制济欢，這里不做介紹

 - (void)applicationDidEnterBackground:(UIApplication *)application{

    UIApplication* app = [UIApplication sharedApplication];
    __block  UIBackgroundTaskIdentifier bgTask;
    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
        dispatch_async(dispatch_get_main_queue(), ^{
            if (bgTask != UIBackgroundTaskInvalid)
            {
                bgTask = UIBackgroundTaskInvalid;
            }
        });
    }];
    
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_async(dispatch_get_main_queue(), ^{
            if (bgTask != UIBackgroundTaskInvalid)
            {
                bgTask = UIBackgroundTaskInvalid;
            }
        });
    });
}

四赠堵、總結(jié)

這個框架使用起來不難，只是在使用的時候需要考慮的情況有些多,理清思路就好了船逮，如有不足之處顾腊，希望多多指教 。