這篇文章主要介紹以下幾個技術(shù)點：

• 使用CocoaAsyncSocket進(jìn)行socket連接
• - (void)startTLS:(NSDictionary *)tlsSettings這個字典內(nèi)容相關(guān)設(shè)置，(https的設(shè)置）
• HTTP請求頭和請求體的自定義設(shè)置（其實就是拼接的一長串帶指定格式的字符串轉(zhuǎn)換成data）
• 對網(wǎng)絡(luò)請求參數(shù)的暫存高蜂，應(yīng)對多條網(wǎng)絡(luò)請求同時發(fā)生的情況

具體實現(xiàn)：

Cocoa框架里，無論是用OS層基于 C 的BSD socket還是用對BSD socket進(jìn)行了輕量級的封裝的CFNetwork创南，對于我這種C語言不及格的同學(xué)，那都是極其痛苦的體驗志电，因此我們就用CocoaAsyncSocket來進(jìn)行socket連接驯鳖，完全OC風(fēng)格，非常愉快竭望。

• 你需要用CocoaPods導(dǎo)入這個庫：

source 'https://github.com/CocoaPods/Specs.git'
source 'https://github.com/Artsy/Specs.git'

platform :ios, ‘9.0’

target ‘你的項目名稱’ do

pod 'CocoaAsyncSocket'

end

• 而后我們新建一個DCSocketManager類來管理這個類的一些代理方法，并生成一個本類的單例裕菠，單例就不再寫了（自己寫吧網(wǎng)上很多）：

.h文件里沒有什么內(nèi)容只是暴露了一個供外界調(diào)用的請求接口咬清，后面介紹，主要是.m文件里的擴(kuò)展屬性：

@interface DCSocketManager()  <GCDAsyncSocketDelegate>
{
    NSString       *_serverHost;//IP或者域名
    int             _serverPort;//端口奴潘，https一般是443
    GCDAsyncSocket *_asyncSocket;//一個全局的對象
}
@property (nonatomic, strong) NSMutableData     *sendData;//最終拼接好的需要發(fā)送出去的數(shù)據(jù)
@property (nonatomic, copy)   NSString          *uriString;//具體請求哪個接口旧烧，比如https://xxx.xxxxx.com/verificationCode里的verificationCode
@property (nonatomic, strong) NSDictionary      *paramters;//Body里面需要傳遞的參數(shù)
@property (nonatomic, copy)   CompletionHandler  completeHandler;//收到返回數(shù)據(jù)后的回調(diào)Block
@property (nonatomic, strong) NSMutableArray *dcNetArr;//網(wǎng)絡(luò)請求參數(shù)的暫存數(shù)組，后面會用到
@end

GCDAsyncSocketDelegate代理的實現(xiàn)：

@implementation DCSocketManager

Singleton_Implementation(DCSocketManager)//單例

- (instancetype)init {//對socket進(jìn)行初始化
    if (self = [super init]) {
        _serverHost = @"xxx.xxxxxx.com";
        _serverPort = 443;
        _asyncSocket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue() socketQueue:nil];
        _dcNetArr = [NSMutableArray arrayWithCapacity:20];
    }
    return self;
}

#pragma mark GCDAsyncSocketDelegate method

- (void)socketDidDisconnect:(GCDAsyncSocket *)sock withError:(NSError *)err
{//斷開連接時會調(diào)用
    NSLog(@"didDisconnect...");
    if (self.dcNetArr.count > 0) {
        [_asyncSocket connectToHost:_serverHost onPort:_serverPort error:nil];
    }
}

- (void)socket:(GCDAsyncSocket *)sock didConnectToHost:(NSString *)host port:(uint16_t)port
{//連接上服務(wù)器時會調(diào)用
    [self doTLSConnect:sock];//連接上服務(wù)器就要進(jìn)行tls認(rèn)證画髓，后面介紹掘剪，如果只是http連接就不需要這句
   NSLog(@"didConnectToHost: %@, port: %d", host, port);
    if (self.dcNetArr.count > 0) {
        DCNetCache *net = [self.dcNetArr firstObject];
        self.uriString = net.uri;
        self.paramters = net.params;
        self.completeHandler = net.completeHandler;
        [self.dcNetArr removeObjectAtIndex:0];
    }
    [sock writeData:self.sendData withTimeout:-1 tag:0];//往服務(wù)器傳遞請求數(shù)據(jù)，之后會介紹self.sendData的拼接
    [sock readDataWithTimeout:-1 tag:0];//馬上讀取一下
}

- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{//讀取到返回數(shù)據(jù)時會調(diào)用
    NSLog(@"didReadData length: %lu, tag: %ld", (unsigned long)data.length, tag);
    if (nil != self.completeHandler) {//如果請求成功奈虾，讀取到服務(wù)器返回的data數(shù)據(jù)一般是一串字符串夺谁，需要根據(jù)返回數(shù)據(jù)格式做相應(yīng)處理解析出來
        NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
        //NSLog(@"%@", string);
        NSRange start = [string rangeOfString:@"{"];
        NSRange end = [string rangeOfString:@"}\r\n"];
        NSString *sub;
        if (end.location != NSNotFound && start.location != NSNotFound) {//如果返回的數(shù)據(jù)中不包含以上符號，會崩潰
            sub = [string substringWithRange:NSMakeRange(start.location, end.location-start.location+1)];//這就是服務(wù)器返回的body體里的數(shù)據(jù)
            NSData *subData = [sub dataUsingEncoding:NSUTF8StringEncoding];;
            NSDictionary *subDic = [NSJSONSerialization JSONObjectWithData:subData options:0 error:nil];
            self.completeHandler(subDic);
        }
    }
    [sock readDataWithTimeout:-1 tag:0];
}

- (void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag
{//成功發(fā)送數(shù)據(jù)時會調(diào)用
    NSLog(@"didWriteDataWithTag: %ld", tag);
    [sock readDataWithTimeout:-1 tag:tag];
}

- (void)socketDidSecure:(GCDAsyncSocket *)sock 
{//https安全認(rèn)證成功時會調(diào)用
    NSLog(@"SSL握手成功肉微，安全通信已經(jīng)建立連接!");
}
@end

這里重點說一下sendData這個屬性的拼接（很重要匾鸥，這里的格式?jīng)Q定了你發(fā)送的請求數(shù)據(jù)是否被服務(wù)器認(rèn)可，并給你返回信息碉纳，相當(dāng)于NSURLRequest的作用,其實就是拼接一個http協(xié)議）：

- (NSMutableData *)sendData {
    NSMutableData *packetData = [[NSMutableData alloc] init];
    NSData *crlfData = [@"\r\n" dataUsingEncoding:NSUTF8StringEncoding];//回車換行是http協(xié)議中每個字段的分隔符

    [packetData appendData:[[NSString stringWithFormat:@"GET /%@ HTTP/1.1", self.uriString] dataUsingEncoding:NSUTF8StringEncoding]];//拼接的請求行
    [packetData appendData:crlfData];//每個字段后面都要跟一個回車換行

    [packetData appendData:[@"DCVer: 1" dataUsingEncoding:NSUTF8StringEncoding]];//拼接的請求頭字段勿负，這個鍵值對和服務(wù)器協(xié)商內(nèi)容，一般不止一個
    [packetData appendData:crlfData];
    [packetData appendData:[@"DCAid: test" dataUsingEncoding:NSUTF8StringEncoding]];//拼接的請求頭字段劳曹，這個鍵值對和服務(wù)器協(xié)商內(nèi)容奴愉，一般不止一個
    [packetData appendData:crlfData];
    
    [packetData appendData:[@"Content-Type: application/json; charset=utf-8" dataUsingEncoding:NSUTF8StringEncoding]];//發(fā)送數(shù)據(jù)的格式
    [packetData appendData:crlfData];
    
    [packetData appendData:[@"User-Agent: GCDAsyncSocket8.0" dataUsingEncoding:NSUTF8StringEncoding]];//代理類型，用來識別用戶的操作系統(tǒng)及版本等信息铁孵，這里我隨便填的锭硼，一般情況沒什么用
    [packetData appendData:crlfData];
    
    [packetData appendData:[@"Host: xxx.xxxxxx.com" dataUsingEncoding:NSUTF8StringEncoding]];//IP或者域名
    [packetData appendData:crlfData];
    
    NSError *error;
    NSData *bodyData = [NSJSONSerialization dataWithJSONObject:self.paramters
                                                       options:0
                                                         error:&error];
    NSString *bodyString = [[NSString alloc] initWithData:bodyData encoding:NSUTF8StringEncoding];//生成請求體的內(nèi)容
    [packetData appendData:[[NSString stringWithFormat:@"Content-Length: %ld", bodyString.length] dataUsingEncoding:NSUTF8StringEncoding]];//說明請求體內(nèi)容的長度
    [packetData appendData:crlfData];
    
    [packetData appendData:[@"Connection:close" dataUsingEncoding:NSUTF8StringEncoding]];
    [packetData appendData:crlfData];
    [packetData appendData:crlfData];//注意這里請求頭拼接完成要加兩個回車換行
  //以上http頭信息就拼接完成，下面繼續(xù)拼接上body信息
    NSString *encodeBodyStr = [NSString stringWithFormat:@"%@\r\n\r\n", bodyString];//請求體最后也要加上兩個回車換行說明數(shù)據(jù)已經(jīng)發(fā)送完畢
    [packetData appendData:[encodeBodyStr dataUsingEncoding:NSUTF8StringEncoding]];
    return packetData;
}

以上就是建立HTTP連接收發(fā)數(shù)據(jù)的全部內(nèi)容库菲，如果不需要支持https的話，這個GET請求已經(jīng)可以完成志膀，下面介紹進(jìn)行https連接需要進(jìn)行的設(shè)置(在.m文件里實現(xiàn))：（上面提到的[self doTLSConnect:sock]這個方法）

- (void)doTLSConnect:(GCDAsyncSocket *)sock {
    //HTTPS
    NSMutableDictionary *sslSettings = [[NSMutableDictionary alloc] init];
    NSData *pkcs12data = [[NSData alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"xxx.xxxxxxx.com" ofType:@"p12"]];//已經(jīng)支持https的網(wǎng)站會有CA證書熙宇，給服務(wù)器要一個導(dǎo)出的p12格式證書
    CFDataRef inPKCS12Data = (CFDataRef)CFBridgingRetain(pkcs12data);
    CFStringRef password = CFSTR("xxxxxx");//這里填寫上面p12文件的密碼
    const void *keys[] = { kSecImportExportPassphrase };
    const void *values[] = { password };
    CFDictionaryRef options = CFDictionaryCreate(NULL, keys, values, 1, NULL, NULL);
    
    CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
    
    OSStatus securityError = SecPKCS12Import(inPKCS12Data, options, &items);
    CFRelease(options);
    CFRelease(password);
    
    if (securityError == errSecSuccess) {
        NSLog(@"Success opening p12 certificate.");
    }
    
    CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
    SecIdentityRef myIdent = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);
    SecIdentityRef  certArray[1] = { myIdent };
    CFArrayRef myCerts = CFArrayCreate(NULL, (void *)certArray, 1, NULL);
    [sslSettings setObject:(id)CFBridgingRelease(myCerts) forKey:(NSString *)kCFStreamSSLCertificates];
    [sslSettings setObject:@"api.pandaworker.com" forKey:(NSString *)kCFStreamSSLPeerName];
    [sock startTLS:sslSettings];//最后調(diào)用一下GCDAsyncSocket這個方法進(jìn)行ssl設(shè)置就Ok了
}

至此發(fā)送HTTPS GET請求并且用body傳遞參數(shù)就實現(xiàn)了鳖擒，是不是很神奇。下面封裝一個對外調(diào)用的接口（在.h文件中把這個接口暴露出去就行了）：

- (void)getRequestUriName:(NSString *)uri Param:(NSDictionary *)params Complete:(CompletionHandler)handler{
    DCNetCache *net = [[DCNetCache alloc] initWithUri:uri Params:params CompleteHandler:handler];
    [self.dcNetCacheArr addObject:net];
    [_asyncSocket connectToHost:_serverHost onPort:_serverPort error:nil];
}

** 其中的DCNetCache類用來暫存網(wǎng)絡(luò)請求的參數(shù)烫止，它是這樣子滴：**

typedef void(^CompletionHandler)(NSDictionary *response);
@interface DCNetCache : NSObject

@property (nonatomic, copy) NSString *uri;
@property (nonatomic, strong) NSDictionary *params;
@property (nonatomic, copy) CompletionHandler completeHandler;

- (instancetype)initWithUri:(NSString *)uri Params:(NSDictionary *)params CompleteHandler:(CompletionHandler)handler;

@end

@implementation DCNetCache

- (instancetype)initWithUri:(NSString *)uri Params:(NSDictionary *)params CompleteHandler:(CompletionHandler)handler{
    self = [super init];
    if (self) {
        _uri = uri;
        _params = params;
        _completeHandler = handler;
    }
    return self;
}
@end

這樣子就大功告成了蒋荚，注意把上面的host換成自己的，這里還有許多不完善的地方馆蠕，我只是實現(xiàn)了簡單的GET請求并暫存請求參數(shù)期升，至于你需要其他的功能自己加上就是了。

附一篇講GCDAsyncSocket的干貨文章互躬，非常值得一讀