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AFN 3.x的学习

AFN 3.x的学习

作者: Hunter琼 | 来源:发表于2018-10-25 13:14 被阅读19次

    AFN 3.0框架示意图:


    图片来自网络.png

    AFN 3.x模块划分

    • 网络通信模块(AFURLSessionManger)
      AFURLSessionManger.h 
      /**
The managed session.管理session对象
*/
@property (readonly, nonatomic, strong) NSURLSession *session;
/**
The operation queue on which delegate callbacks are run.  代理返回的NSOperationQueue(队列)
*/
@property (readonly, nonatomic, strong)NSOperationQueue *operationQueue;
/* 解析网络返回的数据对象,遵循AFURLResponseSerialization协议*/
@property (nonatomic, strong) id <AFURLResponseSerialization> responseSerializer;
 /*
 用于处理网络链接安全策略的AFSecurityPolicy对象
  */
 @property (nonatomic, strong) AFSecurityPolicy  * securityPolicy;
/*
用于检测网络数据的AFNetworkReachabilityManager的对象
 */
@property (readwrite, nonatomic, strong) AFNetworkReachabilityManager *reachabilityManager
/**
当前数据tasks会话
**/
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDataTask *> *dataTasks
/**
当前上传tasks会话
**/
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDataTask *> *uploadTasks
/**
当前下载tasks会话
**/
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDataTask *> *downloadTasks
 /**
 1 设置Session的Call Back(回调函数:就是那些会被主线程挂起来的代码。异步任务必须指定回调函数，当主线程开始执行异步任务，就是执行对应的回调函数)队列
 2 completionQueue:设置completion block队列,默认是main block
 3 completionGroup: 设置completion group队列组
 4 nullable:对象可以为NULL或nil,和swift中optional类型中的!活?类似
 **/
@property (nonatomic, strong, nullable) dispatch_queue_t completionQueue;
@property (nonatomic, strong, nullable) dispatch_queue_t completionGroup
/**
在创建后台任务上传时,有时候会返回nil,遵循苹果的建议,在创建失败的时候,会重新创建联系,次数默认为3次,如果有需要的话设置该属性为YES
**/
@property (nonatomic, assign) BOOL attemptsToRecreateUploadTasksForBackgroundSessions;
 NS_DESIGNATED_INITIALIZER:警告开发者需要实现   这个初始化
 /**
  默认会话 defaultSessionConfiguration:工作模式类似与NSURLConnection,使用磁盘缓存策略,使用用户   keychain中保存证书认证和授权
 瞬时会话模式ephemeralSessionConfirguration:改模式不会使用磁盘保存任何数据,所有的会话,证书,cookie都保持在RAM中,当程序会话消失后,这些缓存数据就会被清空
 backgorundSessionConfigureation:后台会话模式,一般  用户后台上传和下载
**/
NSURLSessionConfiguration *configuration =  [NSURLSessionConfiguration   defaultSessionConfiguration];
 //TODO set the default HTTP headers
 /**  客户端接受服务端发来的cookie   */
 configuration.HTTPShouldSetCookies = YES;
/**   如果设置成YES,则允许不必等到response,就可以发送一个请求,这会大大提高网络请求效率,但是也有问题,因为客户端无法正确匹配请求和响应,所以这依赖于服务器必须保证和客户端响应请求顺序一致,如果保证不了这点,就会请求和响应混乱  */
 configuration.HTTPShouldUsePipelining = NO;
 configuration.requestCachePolicy = NSURLRequestUseProtocolCachePolicy;
/** 
allowsCellularAccess:  是否允许使用蜂窝链接 
  discretionary:是否当前程序在后台运行时由系统自己的最佳网络配置,可以节省蜂窝链接的宽带,会把wifi和电源可用性考虑在内,建议使用discretionary属性.
*/
  configuration.allowsCellularAccess = YES;
 configuration.discretionary = YES
 configuration.timeoutIntervalForRequest = 60.0;
 configuration.URLCache = [AFImageDownloader defaultURLCache]
- (instancetype)initWithSessionConfiguration:(nullable NSURLSessionConfiguration *)configuration NS_DESIGNATED_INITIALIZER
/**
NSURLSessionDataTask:是抽象类   NSURLSessionTask的子类,主要是用来获取数据,可以胜任上传和下载的任务
**/
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
                         completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject,  NSError * _Nullable error))completionHandle
/**
根据ileURL创建reqeust
在ios7中,有时候创建NSURLSessionUploadTask task会失败,Apple建议,可重新尝试连接,尝试次数默认为3次
**/
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
                                      fromFile:(NSURL *)fileURL
                                      progress:(void (^)(NSProgress *uploadProgress)) uploadProgressBlock
                             completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
      AFURLSessionManger.m
       - (instancetype)initWithSessionConfiguration:(NSURLSessionConfiguration *)configuration {
    self = [super init]; 
    if (!self) {
        return nil;
    }

    if (!configuration) {
        configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    }

    self.sessionConfiguration = configuration;

    self.operationQueue = [[NSOperationQueue alloc] init];
    self.operationQueue.maxConcurrentOperationCount = 1;

    self.session = [NSURLSession sessionWithConfiguration:self.sessionConfiguration delegate:self delegateQueue:self.operationQueue];
/**  各种响应转码 */
    self.responseSerializer = [AFJSONResponseSerializer serializer];
/**   默认安全策略**/
    self.securityPolicy = [AFSecurityPolicy defaultPolicy];

#if !TARGET_OS_WATCH
    self.reachabilityManager = [AFNetworkReachabilityManager sharedManager];
#endif

    self.mutableTaskDelegatesKeyedByTaskIdentifier = [[NSMutableDictionary alloc] init];
/** NSLock用于协调多个多线程操作锁 ,是一种同步机制,防止在多任务的情况下对共享资源的脏读和脏写 ,执行多线程时用于强行限制资源访问的同步机制 */
    self.lock = [[NSLock alloc] init];
    self.lock.name = AFURLSessionManagerLockName;
/**  异步获取当前session所有未完成的task */
    [self.session getTasksWithCompletionHandler:^(NSArray *dataTasks, NSArray *uploadTasks, NSArray *downloadTasks) {
        for (NSURLSessionDataTask *task in dataTasks) {
            [self addDelegateForDataTask:task uploadProgress:nil downloadProgress:nil completionHandler:nil];
        }

        for (NSURLSessionUploadTask *uploadTask in uploadTasks) {
            [self addDelegateForUploadTask:uploadTask progress:nil completionHandler:nil];
        }

        for (NSURLSessionDownloadTask *downloadTask in downloadTasks) {
            [self addDelegateForDownloadTask:downloadTask progress:nil destination:nil completionHandler:nil];
        }
    }];

    return self;
}

/**
只要地址为https,则执行这个协议方法,告诉系统,是否信任证书
NSURLAuthenticationChallenge:认证认证
NSURLSessionAuthChallengeDisposition:
1 NSURLSessionAuthChallengeUserCrednetial 使用证书
2 NSURLSessionAuthChallengeDefaultHanding 忽略证书
3 NSURLSessionAuthChallengeCancelAuthenticationChallenge 忽略证书,并拒绝请求这次请求
4 NSURLSessionAuthChallengeRejectProtectionSpace 拒绝当前请求,下一次在询问
*/
- (void)URLSession:(NSURLSession *)session
didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge
 completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential *credential))completionHandler
{
  
    NSURLSessionAuthChallengeDisposition disposition = NSURLSessionAuthChallengePerformDefaultHandling;
    __block NSURLCredential *credential = nil;

    if (self.sessionDidReceiveAuthenticationChallenge) {
        disposition = self.sessionDidReceiveAuthenticationChallenge(session, challenge, &credential);
    } else {
  /**  判断证书是否信任 */
        if 
([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
   
            if ([self.securityPolicy evaluateServerTrust:challenge.protectionSpace.serverTrust forDomain:challenge.protectionSpace.host]) {
                credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
                if (credential) {
                    disposition = NSURLSessionAuthChallengeUseCredential;
                } else {
                    disposition = NSURLSessionAuthChallengePerformDefaultHandling;
                }
            } else {
                disposition = NSURLSessionAuthChallengeRejectProtectionSpace;
            }
        } else {
            disposition = NSURLSessionAuthChallengePerformDefaultHandling;
        }
    }
/**   告诉系统,认证情况*/
    if (completionHandler) {
        completionHandler(disposition, credential);
    }
}

-(NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
                               uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgressBlock
                             downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgressBlock
                            completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject,  NSError * _Nullable error))completionHandler {
    __block NSURLSessionDataTask *dataTask = nil;
/**  
     创建task 
     url_session_manager_create_task_safely:这个函数主要是解决iOS8之前的bug,在这个函数中用到了NSFoundationVersionNumber:比较Foundation框架版本号,iOS升级时Foundation也会提高
*/
    url_session_manager_create_task_safely(^{
        dataTask = [self.session dataTaskWithRequest:request];
    });
/**  NSURLSessionDataTask添加一个delegate:AFURLSessionManagerTaskDelegate  */
    [self addDelegateForDataTask:dataTask uploadProgress:uploadProgressBlock downloadProgress:downloadProgressBlock completionHandler:completionHandler];

    return dataTask;
}
/**
设置代理
**/
- (AFURLSessionManagerTaskDelegate *)delegateForTask:(NSURLSessionTask *)task {
    NSParameterAssert(task);
    AFURLSessionManagerTaskDelegate *delegate = nil;
/** 防止线程被脏写 */
    [self.lock lock];
    delegate = self.mutableTaskDelegatesKeyedByTaskIdentifier[@(task.taskIdentifier)];
    [self.lock unlock];

    return delegate;
}

    AFHTTPSessionManger.h

    /**
GET 请求
*/
 - (nullable NSURLSessionDataTask *)GET:(NSString *)URLString
                            parameters:(nullable id)parameters
                              progress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgress
                               success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
                               failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure
/**
HEAD请求
 用来获取报文首部,和GET差不多,只是响应不会返回主体内容
**/

- (nullable NSURLSessionDataTask *)HEAD:(NSString *)URLString
                    parameters:(nullable id)parameters
                       success:(nullable void (^)(NSURLSessionDataTask *task))success
                       failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure

    AFHTTPSessionManger.m

    - (NSURLSessionDataTask *)GET:(NSString *)URLString
                   parameters:(id)parameters
                     progress:(void (^)(NSProgress * _Nonnull))downloadProgress
                      success:(void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success
                      failure:(void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure
{
/**
 生成一个task
 网络安全策略验证解析失败,直接返回task=nil ,网络请求失败
*/
    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"GET"
                                                        URLString:URLString
                                                       parameters:parameters
                                                   uploadProgress:nil
                                                 downloadProgress:downloadProgress
                                                          success:success
                                                          failure:failure];

    [dataTask resume];

    return dataTask;
}
    • 网路通讯安全策略模块(AFSecuityPolicy)
      AFSecuityPolicy.h
    typedef NS_ENUM(NSUInteger, AFSSLPinningMode) {
  /**  无条件信任证书  */
   AFSSLPinningModeNone,
  /**  对服务端返回的PublicKey(公钥)进行验证   */
   AFSSLPinningModePublicKey,
 /**  对服务端返回的证书和本地证书进行校验 */
   AFSSLPinningModeCertificate,
};
/**
返回SSL Pinning类型  默认`AFSSLPinningModeNone`.
*/
@property (readonly, nonatomic, assign) AFSSLPinningMode SSLPinningMode;

/**
保存所有可用做校验证书集合,AFN默认搜索工程中所以.cer证书,如果定制某些证书,可使用certificatesInBundle在目录下加载证书,然后调用policyWithPinnngMode:withPinnedCertificates创建一个类对象
*/
@property (nonatomic, strong, nullable) NSSet <NSData *> *pinnedCertificates;
/**
是否使用过期或无效证书,默认为 `NO`.
*/
@property (nonatomic, assign) BOOL allowInvalidCertificates;
/**
是否校验证书中的域名domain
*/
@property (nonatomic, assign) BOOL validatesDomainName;
/**
 返回指定的的bundle证书,必须实现这个方法,并使用policyWithPinningMode:withPinnedCertificates方法创建实例对象
*/
+ (NSSet <NSData *> *)certificatesInBundle:(NSBundle *)bundle;
/**
默认的实例对象
1 不允许无效或者过期的证书
2 验证域名
3 不对证书和公钥进行校验
*/
+ (instancetype)defaultPolicy;

/**
创建SSL认证实例
@param pinningMode SSL Pinning类型
*/
+ (instancetype)policyWithPinningMode:(AFSSLPinningMode)pinningMode;

/**
创建SSL认证实例
@param pinningMode SSL Pinning类型.
@param pinnedCertificates :可用做校验证书集合
*/
+ (instancetype)policyWithPinningMode:(AFSSLPinningMode)pinningMode withPinnedCertificates:(NSSet <NSData *> *)pinnedCertificates;
/**
核心证书校验方法
**/
- (BOOL)evaluateServerTrust:(SecTrustRef)serverTrust
                 forDomain:(nullable NSString *)domain

    AFSecuityPolicy.m

    /**
获取二进制公钥:NSdata ----> CFDataRef ----> SecCertificateCreateWithData----->SecTrustCopyPublicKey(SecTrustRef)
*/
static id AFPublicKeyForCertificate(NSData *certificate) {
    id allowedPublicKey = nil;
    SecCertificateRef allowedCertificate;
    SecCertificateRef allowedCertificates[1];
    CFArrayRef tempCertificates = nil;
    SecPolicyRef policy = nil;
    SecTrustRef allowedTrust = nil;
    SecTrustResultType result;
/**  根据二进制certificate生成 SecCertificateRef类型证书*/
    allowedCertificate = SecCertificateCreateWithData(NULL, (__bridge CFDataRef)certificate);
 /**
如果allowedCertificate为空,则执行标记_out后面的代码
__Require_Quiet:这个宏定义usr/include/AssertMacros,当返回为false,执行标记后面的代码
 **/
    __Require_Quiet(allowedCertificate != NULL, _out);
 /**
 给allowedCertificates赋值
 */
    allowedCertificates[0] = allowedCertificate;
 /**
 新建CFArrayCreate tempCertificates
 */
    tempCertificates = CFArrayCreate(NULL, (const void **)allowedCertificates, 1, NULL);
  /**
   新建policy为X5.09
   */
    policy = SecPolicyCreateBasicX509();
/**
创建SecTrustRef对象,如果错误则跳到_out标记处
 __Require_noErr_Quiet:若抛出异常则执行标记后面代码
**/
 __Require_noErr_Quiet(SecTrustCreateWithCertificates(tempCertificates, policy, &allowedTrust), _out);
/**
证书校验,如失败则跳到_out处
**/
 __Require_noErr_Quiet(SecTrustEvaluate(allowedTrust, &result), _out);
/**  在SecTrustRef获取公钥   */
    allowedPublicKey = (__bridge_transfer id)SecTrustCopyPublicKey(allowedTrust);

_out:
    if (allowedTrust) {
        CFRelease(allowedTrust);
    }

    if (policy) {
        CFRelease(policy);
    }

    if (tempCertificates) {
        CFRelease(tempCertificates);
    }

    if (allowedCertificate) {
        CFRelease(allowedCertificate);
    }

    return allowedPublicKey;
}

/**
返回服务端是否可信任
**/
static BOOL AFServerTrustIsValid(SecTrustRef serverTrust) {
    BOOL isValid = NO;
    SecTrustResultType result;
    __Require_noErr_Quiet(SecTrustEvaluate(serverTrust, &result), _out);
/** 
kSecTrustResultUnspecified :不是自己设的证书就通过
kSecTrustResultProceed:用户自己生成证书通过,比如信任弹框
   */
    isValid = (result == kSecTrustResultUnspecified || result == kSecTrustResultProceed);

_out:
    return isValid;
}

    • 网络监听模块(AFNnetworkReachablityManger)

      typedef NS_ENUM(NSInteger, AFNetworkReachabilityStatus) {
AFNetworkReachabilityStatusUnknown          = -1,//未知网路
AFNetworkReachabilityStatusNotReachable     = 0,//网络不可达到
AFNetworkReachabilityStatusReachableViaWWAN = 1,//蜂窝网络
AFNetworkReachabilityStatusReachableViaWiFi = 2,
};

      AFNnetworkReachablityManger提供了许多监听的实例方法,最常用的是sharedManger,还可以用调用mangerForAddress或者mangerForDomain方法来监控套接地址和域名地址.

    /**
  监听结果回调,调用starMonitoring变开始监听,调用stopMonitoring关闭监听
*/
- (void)setReachabilityStatusChangeBlock:(nullable void (^)(AFNetworkReachabilityStatus status))block

    • 网络通讯信息序列化/反序列化模块(AFURLResponseSerialization)

    • UIKit扩展模块

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