• 使用AsyncSocket的時候可以做一層封裝，根據(jù)需求提供幾個接口出來。比如：連接、斷開連接、發(fā)送消息等等。還有接受消息，接受到的消息可以通過通知、代理、block等傳出去。
• 對AsyncSocket使用.一般來說，一個用戶只需要建立一個socket長連接，所以可以用單例類方便使用。

使用AsyncSocket

1.創(chuàng)建socket的單例類

//在LGSocketServe.h 
#import <Foundation/Foundation.h>
#import "AsyncSocket.h"
#import "GCDAsyncSocket.h"
@interface LGSocketServe : NSObject
//創(chuàng)建屬性 用于連接
@property (nonatomic, strong, readonly) GCDAsyncSocket          *socket;
@property (nonatomic, copy,   readonly) NSString                *socketHost;
@property (nonatomic, assign, readonly) uint16_t                socketPort;

//創(chuàng)建單列類
+(instancetype)shareSocket;
@end



//在LGSocketServe.m
#import "LGSocketServe.h"
#import <UIKit/UIKit.h>

@interface LGSocketServe ()

@property (nonatomic, strong, readwrite) GCDAsyncSocket         *socket;
@property (nonatomic, copy,   readwrite) NSString               *socketHost;
@property (nonatomic, assign, readwrite) uint16_t               socketPort;

@end

@implementation LGSocketServe 

+(instancetype)shareSocket
{
    static dispatch_once_t onceToken;
    static LGSocketServe *socket;
    dispatch_once(&onceToken, ^{
        socket = [[LGSocketServe alloc]init];
    });
    return socket;
}
- (instancetype)init
{
    self = [super init];
    if (self) {
        self.socket = [[GCDAsyncSocket alloc]initWithDelegate:self delegateQueue:dispatch_get_global_queue(0, 0)];
    }
    return self;
}

//創(chuàng)建連接
- (void)connected:(NSString *)host onPort:(uint16_t)port error:(NSError *)error{
    self.socketHost = host;
    self.socketPort = port;
    //必須確認(rèn)在斷開連接的情況下，進(jìn)行連接
    if (self.socket.isDisconnected) {
        [self.socket connectToHost:self.socketHost onPort:self.socketPort error:nil];
    }else{
        [self.socket disconnect];
        [self.socket connectToHost:self.socketHost onPort:self.socketPort error:nil];
    }
    [self.socket connectToHost:host onPort:port error:nil];
}
//心跳連接
-(void)longConnectToSocket{
    // 根據(jù)服務(wù)器要求發(fā)送固定格式的數(shù)據(jù)，假設(shè)為指令@"longConnect"，但是一般不會是這么簡單的指令
    NSString *longConnect = @"longConnect\r\n";
    NSData   *dataStream  = [longConnect dataUsingEncoding:NSUTF8StringEncoding];
    [self.socket writeData:dataStream withTimeout:-1 tag:0];
}
//連接成功
- (void)socket:(GCDAsyncSocket *)sock didConnectToHost:(NSString *)host port:(uint16_t)port
{
    //每隔特定時間向服務(wù)器發(fā)送心跳包
    //在longConnectToSocket方法中進(jìn)行長連接需要向服務(wù)器發(fā)送特定信息
    self.longConnectTimer
    = [NSTimer timerWithTimeInterval:kSocketConnectTimerTimeInterval
                              target:self
                            selector:@selector(longConnectToSocket)
                            userInfo:nil
                             repeats:YES];
    [[NSRunLoop currentRunLoop] addTimer:self.longConnectTimer
                                 forMode:NSRunLoopCommonModes];
}
//斷開連接
- (void)disConnected{

    [self.socket disconnect];
}
//斷開之后重新連接
- (void)socketDidDisconnect:(GCDAsyncSocket *)sock withError:(NSError *)err
{
    //這里可以列舉枚舉值
    //因用戶自動斷開 不自動連接
    if (self.offlineError == SZYSocketOfflineByServer) {
        [self.longConnectTimer invalidate];
        self.longConnectTimer = nil;
        [self.socket setDelegate:nil];
        [self.socket disconnect];
    //因服務(wù)器原因斷開 自動連接
    }else if (self.offlineError == SZYSocketOfflineByServer){
    
        [self.longConnectTimer invalidate];
        self.longConnectTimer = nil;
        [self.socket setDelegate:nil];
        [self.socket disconnect];
        [self.socket setDelegate:self];
        [self.socket connectToHost:self.socketHost
                            onPort:self.socketPort
                             error:nil];
    //因Wifi原因斷開 不自動連接
    }else{
        [self.longConnectTimer invalidate];
        self.longConnectTimer = nil;
        [self.socket setDelegate:nil];
        [self.socket disconnect];
    }
    
}
//寫入數(shù)據(jù)
- (void)writeData:(NSData *)data withTimeout:(NSTimeInterval)timeout tag:(long)tag{

    [self.socket writeData:data withTimeout:-1 tag:100];
}
- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag {
    NSString *dataString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"讀取到的消息:%@", dataString);
}
//讀取數(shù)據(jù)
- (void)readDataToData:(NSData *)data withTimeout:(NSTimeInterval)timeout tag:(long)tag{
    [self.socket readDataToData:data withTimeout:-1 tag:100];
    
}
- (void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag {
    NSLog(@"didWriteDataWithTag");
}

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