AFNetworking 3.x 详解三

AFSecurityPolicy

AFSecurityPolicy用于公钥安全连接和对X.509证书的服务器信任验证，数字证书的格式遵循X.509标准，X.509是由国际电信联盟（ITU-T）制定的数字证书标准。

AFSSLPinningMode SSLPinningMode 根据固定的SSL证书对服务器信任进行评估的标准,默认为“AFSSLPinningModeNone”。
NSSet <NSData *> *pinnedCertificates 用于根据SSL连接模式评估服务器信任的证书。
BOOL allowInvalidCertificates 是否信任服务器无效或过期的SSL证书。默认为“NO”。
validatesDomainName 是否验证证书CN字段中的域名。默认为“YES”。

#pragma mark -根据severTrust和domain检测服务端发送的证书是否可信
// SecTrustRef是一个CoreFoundation类型，用于对服务器端传来的X.509证书评估
- (BOOL)evaluateServerTrust:(SecTrustRef)serverTrust
                  forDomain:(NSString *)domain
{
    //如果domain存在并且允许使用自建证书；证书中的域名有效；SSLPinningMode模式为AFSSLPinningModeNone（不使用SSL pinning）或者本地没有证书文件的时候，则返回NO。也就是说需要验证自签名证书的话，就必须把对应证书导入到本地，并更改AFSSLPinningMode
    if (domain && self.allowInvalidCertificates && self.validatesDomainName && (self.SSLPinningMode == AFSSLPinningModeNone || [self.pinnedCertificates count] == 0)) {
        // https://developer.apple.com/library/mac/documentation/NetworkingInternet/Conceptual/NetworkingTopics/Articles/OverridingSSLChainValidationCorrectly.html
        //  According to the docs, you should only trust your provided certs for evaluation.
        //  Pinned certificates are added to the trust. Without pinned certificates,
        //  there is nothing to evaluate against.
        //
        //  From Apple Docs:
        //          "Do not implicitly trust self-signed certificates as anchors (kSecTrustOptionImplicitAnchors).
        //           Instead, add your own (self-signed) CA certificate to the list of trusted anchors."
        NSLog(@"In order to validate a domain name for self signed certificates, you MUST use pinning.");
        return NO;
    }

    NSMutableArray *policies = [NSMutableArray array];
    if (self.validatesDomainName) {
              // 如果需要验证domain，就使用SecPolicyCreateSSL函数创建验证策略，其中第一个参数为true表示验证整个SSL证书链，第二个参数传入domain，用于判断整个证书链上叶子节点表示的那个domain是否和此处传入domain一致
        [policies addObject:(__bridge_transfer id)SecPolicyCreateSSL(true, (__bridge CFStringRef)domain)];
    } else {
              // 如果不需要验证domain，就使用默认的BasicX509验证策略
        [policies addObject:(__bridge_transfer id)SecPolicyCreateBasicX509()];
    }

    SecTrustSetPolicies(serverTrust, (__bridge CFArrayRef)policies);
            // 如果SSLPinningMode为 AFSSLPinningModeNone，表示不使用SSL pinning，是否允许自建证书或者AFServerTrustIsValid检测serverTrust是否可信任，如果信任，返回YES
    if (self.SSLPinningMode == AFSSLPinningModeNone) {
        return self.allowInvalidCertificates || AFServerTrustIsValid(serverTrust);
    } else if (!AFServerTrustIsValid(serverTrust) && !self.allowInvalidCertificates) {
              // 既不允许自建证书，并且AFServerTrustIsValid又返回NO，那么该serverTrust不能通过验证
        return NO;
    }

    switch (self.SSLPinningMode) {
        case AFSSLPinningModeNone:
        default:
            return NO;
        case AFSSLPinningModeCertificate: {
          //当使用SSL Pinning Mode时，也就是本地导入自检证书时，遍历pinnedCertificates集合中的证书文件，调用AFServerTrustIsValid方法中的SecTrustEvaluate进行验证，如果不能被信任，返回NO；
            NSMutableArray *pinnedCertificates = [NSMutableArray array];
            for (NSData *certificateData in self.pinnedCertificates) {
                [pinnedCertificates addObject:(__bridge_transfer id)SecCertificateCreateWithData(NULL, (__bridge CFDataRef)certificateData)];
            }
            SecTrustSetAnchorCertificates(serverTrust, (__bridge CFArrayRef)pinnedCertificates);

            if (!AFServerTrustIsValid(serverTrust)) {
                return NO;
            }

            //返回顺序是从叶子节点到根节点的可信任的证书链
          NSArray *serverCertificates = AFCertificateTrustChainForServerTrust(serverTrust);
            //从下遍历服务端返回的证书链的证书，如果和本地绑定的证书一致则返回YES
            //从服务器端证书链的根节点往下遍历，因为遍历顺序正好相反，所以使用reverseObjectEnumerator
            for (NSData *trustChainCertificate in [serverCertificates reverseObjectEnumerator]) {
                if ([self.pinnedCertificates containsObject:trustChainCertificate]) {
                    return YES;
                }
            }
            
            return NO;
        }
        case AFSSLPinningModePublicKey: {
                  // AFSSLPinningModePublicKey模式也是使是用证书绑定(SSL Pinning)方式验证，本地要有对应证书，但是验证时只验证证书里的公钥，不验证证书的有效期等信息。只要公钥是正确的就算通过
            NSUInteger trustedPublicKeyCount = 0;
            //从serverTrust中取出对应证书的公钥
            NSArray *publicKeys = AFPublicKeyTrustChainForServerTrust(serverTrust);
            // 依次遍历，如果和客户端绑定证书的公钥一致，就给trustedPublicKeyCount加1
            for (id trustChainPublicKey in publicKeys) {
                for (id pinnedPublicKey in self.pinnedPublicKeys) {
                    if (AFSecKeyIsEqualToKey((__bridge SecKeyRef)trustChainPublicKey, (__bridge SecKeyRef)pinnedPublicKey)) {
                        trustedPublicKeyCount += 1;
                    }
                }
            }
            return trustedPublicKeyCount > 0;
        }
    }
    
    return NO;
}

AFHTTPResponseSerializer

AFHTTPResponseSerializer遵从AFURLRequestSerialization和AFURLResponseSerialization（数据响应序列化，如JSON响应序列化程序可以检查一个可接受的状态代码（2xx范围）和内容类型（application/json），将可用的JSON转化为一个对象）协议，提供一个具体的基本实现URL的查询字符串/表单编码的参数序列化和默认请求头,以及响应状态码和内容类型验证。

对应的他也衍生出一些子类用于解析不同的数据类型：

AFJSONResponseSerializer
AFXMLParserResponseSerializer
AFXMLDocumentResponseSerializer
AFPropertyListResponseSerializer
AFImageResponseSerializer
AFCompoundResponseSerializer

其实他们都是实现了- (id)responseObjectForResponse:(NSURLResponse *)response data:(NSData *)data error:(NSError *__autoreleasing *)error方法，在里面解析成对应需要的数据。

对于**AFHTTPResponseSerializer **:

#pragma mark -

- (BOOL)validateResponse:(NSHTTPURLResponse *)response
                    data:(NSData *)data
                   error:(NSError * __autoreleasing *)error
{
    BOOL responseIsValid = YES;
    NSError *validationError = nil;
//如果不为空并且类型正确则解析
    if (response && [response isKindOfClass:[NSHTTPURLResponse class]]) {
      //解析的acceptableContentTypes不包含响应的IMMEType
        if (self.acceptableContentTypes && ![self.acceptableContentTypes containsObject:[response MIMEType]] &&
            !([response MIMEType] == nil && [data length] == 0)) {

            if ([data length] > 0 && [response URL]) {
                NSMutableDictionary *mutableUserInfo = [@{
                                                          NSLocalizedDescriptionKey: [NSString stringWithFormat:NSLocalizedStringFromTable(@"Request failed: unacceptable content-type: %@", @"AFNetworking", nil), [response MIMEType]],
                                                          NSURLErrorFailingURLErrorKey:[response URL],
                                                          AFNetworkingOperationFailingURLResponseErrorKey: response,
                                                        } mutableCopy];
                if (data) {
                    mutableUserInfo[AFNetworkingOperationFailingURLResponseDataErrorKey] = data;
                }

                validationError = AFErrorWithUnderlyingError([NSError errorWithDomain:AFURLResponseSerializationErrorDomain code:NSURLErrorCannotDecodeContentData userInfo:mutableUserInfo], validationError);
            }

            responseIsValid = NO;
        }

        if (self.acceptableStatusCodes && ![self.acceptableStatusCodes containsIndex:(NSUInteger)response.statusCode] && [response URL]) {
            NSMutableDictionary *mutableUserInfo = [@{
                                               NSLocalizedDescriptionKey: [NSString stringWithFormat:NSLocalizedStringFromTable(@"Request failed: %@ (%ld)", @"AFNetworking", nil), [NSHTTPURLResponse localizedStringForStatusCode:response.statusCode], (long)response.statusCode],
                                               NSURLErrorFailingURLErrorKey:[response URL],
                                               AFNetworkingOperationFailingURLResponseErrorKey: response,
                                       } mutableCopy];

            if (data) {
                mutableUserInfo[AFNetworkingOperationFailingURLResponseDataErrorKey] = data;
            }

            validationError = AFErrorWithUnderlyingError([NSError errorWithDomain:AFURLResponseSerializationErrorDomain code:NSURLErrorBadServerResponse userInfo:mutableUserInfo], validationError);

            responseIsValid = NO;
        }
    }

    if (error && !responseIsValid) {
        *error = validationError;
    }

    return responseIsValid;
}

AFJSONResponseSerializer

self.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", nil];接收类型为"application/json","text/json","text/javascript"

- (id)responseObjectForResponse:(NSURLResponse *)response
                           data:(NSData *)data
                          error:(NSError *__autoreleasing *)error
{
    //如果接收的ContentTypes不正确，或者statusCode不满足                       
    if (![self validateResponse:(NSHTTPURLResponse *)response data:data error:error]) {
        if (!error || AFErrorOrUnderlyingErrorHasCodeInDomain(*error, NSURLErrorCannotDecodeContentData, AFURLResponseSerializationErrorDomain)) {
            return nil;
        }
    }

    // Workaround for behavior of Rails to return a single space for `head :ok` (a workaround for a bug in Safari), which is not interpreted as valid input by NSJSONSerialization.
    // See https://github.com/rails/rails/issues/1742
    BOOL isSpace = [data isEqualToData:[NSData dataWithBytes:" " length:1]];
    //如果返回数据是单个空格则不解析
    if (data.length == 0 || isSpace) {
        return nil;
    }
    
    NSError *serializationError = nil;
    
    id responseObject = [NSJSONSerialization JSONObjectWithData:data options:self.readingOptions error:&serializationError];

    if (!responseObject)
    {
        if (error) {
            *error = AFErrorWithUnderlyingError(serializationError, *error);
        }
        return nil;
    }
    //如果需要移除JSON中key对应的values为空的情况，调用AFJSONObjectByRemovingKeysWithNullValues
    if (self.removesKeysWithNullValues) {
        return AFJSONObjectByRemovingKeysWithNullValues(responseObject, self.readingOptions);
    }

    return responseObject;
}

AFXMLParserResponseSerializer

self.acceptableContentTypes = [[NSSet alloc] initWithObjects:@"application/xml", @"text/xml", nil];对应的ContentType为application/xml 和text/xml

- (id)responseObjectForResponse:(NSHTTPURLResponse *)response
                           data:(NSData *)data
                          error:(NSError *__autoreleasing *)error
{
    if (![self validateResponse:(NSHTTPURLResponse *)response data:data error:error]) {
        if (!error || AFErrorOrUnderlyingErrorHasCodeInDomain(*error, NSURLErrorCannotDecodeContentData, AFURLResponseSerializationErrorDomain)) {
            return nil;
        }
    }
//解析方法是使用NSXMLParser
    return [[NSXMLParser alloc] initWithData:data];
}

AFXMLDocumentResponseSerializer

同理，ContentType为application/xml 和text/xml，不同的地方是使用在MAC_OS_X系统。

- (id)responseObjectForResponse:(NSURLResponse *)response
                           data:(NSData *)data
                          error:(NSError *__autoreleasing *)error
{
    if (![self validateResponse:(NSHTTPURLResponse *)response data:data error:error]) {
        if (!error || AFErrorOrUnderlyingErrorHasCodeInDomain(*error, NSURLErrorCannotDecodeContentData, AFURLResponseSerializationErrorDomain)) {
            return nil;
        }
    }
    //使用NSXMLDocument进行解析
    NSError *serializationError = nil;
    NSXMLDocument *document = [[NSXMLDocument alloc] initWithData:data options:self.options error:&serializationError];

    if (!document)
    {
        if (error) {
            *error = AFErrorWithUnderlyingError(serializationError, *error);
        }
        return nil;
    }
    
    return document;
}

AFPropertyListResponseSerializer

ContentType为"application/x-plist"

- (id)responseObjectForResponse:(NSURLResponse *)response
                           data:(NSData *)data
                          error:(NSError *__autoreleasing *)error
{
    if (![self validateResponse:(NSHTTPURLResponse *)response data:data error:error]) {
        if (!error || AFErrorOrUnderlyingErrorHasCodeInDomain(*error, NSURLErrorCannotDecodeContentData, AFURLResponseSerializationErrorDomain)) {
            return nil;
        }
    }

    if (!data) {
        return nil;
    }
    
    NSError *serializationError = nil;
    //使用NSPropertyListSerialization解析
    id responseObject = [NSPropertyListSerialization propertyListWithData:data options:self.readOptions format:NULL error:&serializationError];
    
    if (!responseObject)
    {
        if (error) {
            *error = AFErrorWithUnderlyingError(serializationError, *error);
        }
        return nil;
    }

    return responseObject;
}

AFImageResponseSerializer

当ContentType为@"image/tiff", @"image/jpeg", @"image/gif", @"image/png", @"image/ico", @"image/x-icon", @"image/bmp", @"image/x-bmp", @"image/x-xbitmap", @"image/x-win-bitmap", MIMEType为"image/png" "image/jpeg"

- (id)responseObjectForResponse:(NSURLResponse *)response
                           data:(NSData *)data
                          error:(NSError *__autoreleasing *)error
{
    if (![self validateResponse:(NSHTTPURLResponse *)response data:data error:error]) {
        if (!error || AFErrorOrUnderlyingErrorHasCodeInDomain(*error, NSURLErrorCannotDecodeContentData, AFURLResponseSerializationErrorDomain)) {
            return nil;
        }
    }

#if TARGET_OS_IOS || TARGET_OS_TV || TARGET_OS_WATCH
    //是否允许自动填充响应图像数据压缩格式(如PNG和JPEG)，当使用`setCompletionBlockWithSuccess:failure:`方法时在iOS上可以显著提高性能,因为它允许在后台建立bitmap representation,而不是在主线程。默认“是”。                        
    if (self.automaticallyInflatesResponseImage) {
        return AFInflatedImageFromResponseWithDataAtScale((NSHTTPURLResponse *)response, data, self.imageScale);
    } else {
        //否则就线程安全的使用imageWithData方法得到image对象
        return AFImageWithDataAtScale(data, self.imageScale);
    }
#else
    // Ensure that the image is set to it's correct pixel width and height
    NSBitmapImageRep *bitimage = [[NSBitmapImageRep alloc] initWithData:data];
    NSImage *image = [[NSImage alloc] initWithSize:NSMakeSize([bitimage pixelsWide], [bitimage pixelsHigh])];
    [image addRepresentation:bitimage];

    return image;
#endif

    return nil;
}

AFCompoundResponseSerializer

可以添加一组responseSerializer

- (id)responseObjectForResponse:(NSURLResponse *)response
                           data:(NSData *)data
                          error:(NSError *__autoreleasing *)error
{
    for (id <AFURLResponseSerialization> serializer in self.responseSerializers) {
      //如果是AFHTTPResponseSerializer则调到下一个
        if (![serializer isKindOfClass:[AFHTTPResponseSerializer class]]) {
            continue;
        }

        NSError *serializerError = nil;
      //根据类型指定去解析
        id responseObject = [serializer responseObjectForResponse:response data:data error:&serializerError];
        if (responseObject) {
            if (error) {
                *error = AFErrorWithUnderlyingError(serializerError, *error);
            }

            return responseObject;
        }
    }

    return [super responseObjectForResponse:response data:data error:error];
}

AFNetworkReachabilityManager

AFNetworkReachabilityManager 是用于监控网络状况的，来看下写法：

AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];
// 设置networkReachabilityStatusBlock，根据返回的网络状态处理
[manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
    NSLog(@"network status '%@'", AFStringFromNetworkReachabilityStatus(status));
}];
// 启动网络监听
[manager startMonitoring];

//首先是创建一个单例
+ (instancetype)sharedManager {
    static AFNetworkReachabilityManager *_sharedManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedManager = [self manager];
    });

    return _sharedManager;
}

+ (instancetype)manager
{
#if (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED >= 90000) || (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 101100)
    struct sockaddr_in6 address;
    bzero(&address, sizeof(address));
    address.sin6_len = sizeof(address);
    address.sin6_family = AF_INET6;
#else
    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_len = sizeof(address);
    address.sin_family = AF_INET;
#endif
    //获取internet环境下套接字的地址
    return [self managerForAddress:&address];
}

+ (instancetype)managerForAddress:(const void *)address {
  //SCNetworkReachability API允许应用程序确定系统当前网络的状态配置和目标主机的可达性，当网络状态发送改变时可以获取到通知
    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr *)address);
    AFNetworkReachabilityManager *manager = [[self alloc] initWithReachability:reachability];

    CFRelease(reachability);
    
    return manager;
}

- (void)startMonitoring {
    [self stopMonitoring];

    if (!self.networkReachability) {
        return;
    }

    __weak __typeof(self)weakSelf = self;
    AFNetworkReachabilityStatusBlock callback = ^(AFNetworkReachabilityStatus status) {
        __strong __typeof(weakSelf)strongSelf = weakSelf;

        strongSelf.networkReachabilityStatus = status;
        if (strongSelf.networkReachabilityStatusBlock) {
            strongSelf.networkReachabilityStatusBlock(status);
        }

    };
    //SCNetworkReachability包含指定数据的结构和回调,Block_copy,Block_release
    SCNetworkReachabilityContext context = {0, (__bridge void *)callback, AFNetworkReachabilityRetainCallback, AFNetworkReachabilityReleaseCallback, NULL};
    //分配一个target给到client,当目标的可达性变化时接收回调
    SCNetworkReachabilitySetCallback(self.networkReachability, AFNetworkReachabilityCallback, &context);
//     Schedules the given target with the given run loop and mode
    SCNetworkReachabilityScheduleWithRunLoop(self.networkReachability, CFRunLoopGetMain(), kCFRunLoopCommonModes);
    //放入后台线程执行，改变则发送通知
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0),^{
        SCNetworkReachabilityFlags flags;
        if (SCNetworkReachabilityGetFlags(self.networkReachability, &flags)) {
            AFPostReachabilityStatusChange(flags, callback);
        }
    });
}

最后编辑于：2017.12.08 21:29:10

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