AFNetworking - AFHTTPSessionMana

AFHTTPSessionManager继承的是AFURLSessionManager类，它封装的是AF中最外层的我们经常使用的方法。

最开始是一些实例化方法

//NSURLSessionConfiguration为NSURLSession配置一些请求所需要的策略,cookies，缓存，超时，是否允许蜂窝网络
- (instancetype)initWithSessionConfiguration:(NSURLSessionConfiguration *)configuration {
    return [self initWithBaseURL:nil sessionConfiguration:configuration];
}

- (instancetype)initWithBaseURL:(NSURL *)url
           sessionConfiguration:(NSURLSessionConfiguration *)configuration
{
    self = [super initWithSessionConfiguration:configuration];
    if (!self) {
        return nil;
    }

    // Ensure terminal slash for baseURL path, so that NSURL +URLWithString:relativeToURL: works as expected
    //自动拼接baseURL和urlPath
    if ([[url path] length] > 0 && ![[url absoluteString] hasSuffix:@"/"]) {//如果urlPath前面没有“/”，可能会造成拼接内容丢失
        url = [url URLByAppendingPathComponent:@""];//防止出现url内容丢失，保持拼接完整
    }

    self.baseURL = url;

    //请求和返回数据的序列化器
    self.requestSerializer = [AFHTTPRequestSerializer serializer];
    self.responseSerializer = [AFJSONResponseSerializer serializer];

    return self;
}

如果有特殊的 content-type 的请求或者响应，需要自定义序列化器，以下两个set方法设置请求和响应序列化器

- (void)setRequestSerializer:(AFHTTPRequestSerializer <AFURLRequestSerialization> *)requestSerializer {

    //#define NSParameterAssert(condition) NSAssert((condition), @"Invalid parameter not satisfying: %@", @#condition)
    //断言，如果序列化器为空抛出异常，并且提示
    NSParameterAssert(requestSerializer);

    _requestSerializer = requestSerializer;
}

- (void)setResponseSerializer:(AFHTTPResponseSerializer <AFURLResponseSerialization> *)responseSerializer {
    NSParameterAssert(responseSerializer);

    [super setResponseSerializer:responseSerializer];
}

自定义安全策略set方法

- (void)setSecurityPolicy:(AFSecurityPolicy *)securityPolicy {
    //如果SSLPinningMode是有安全策略的，但是请求的 scheme 不是 https 的，那么就要报错。因为安全策略必须要在 https 模式下
    if (securityPolicy.SSLPinningMode != AFSSLPinningModeNone && ![self.baseURL.scheme isEqualToString:@"https"]) {
        NSString *pinningMode = @"Unknown Pinning Mode";
        switch (securityPolicy.SSLPinningMode) {
            case AFSSLPinningModeNone:        pinningMode = @"AFSSLPinningModeNone"; break;
            case AFSSLPinningModeCertificate: pinningMode = @"AFSSLPinningModeCertificate"; break;
            case AFSSLPinningModePublicKey:   pinningMode = @"AFSSLPinningModePublicKey"; break;
        }
        NSString *reason = [NSString stringWithFormat:@"A security policy configured with `%@` can only be applied on a manager with a secure base URL (i.e. https)", pinningMode];
        @throw [NSException exceptionWithName:@"Invalid Security Policy" reason:reason userInfo:nil];
    }

    [super setSecurityPolicy:securityPolicy];
}

这里就不一一列出GET，POST等等请求方法了，它们都调用了一个统一的会话数据任务创建方法

- (NSURLSessionDataTask *)dataTaskWithHTTPMethod:(NSString *)method
                                       URLString:(NSString *)URLString
                                      parameters:(nullable id)parameters
                                         headers:(nullable NSDictionary <NSString *, NSString *> *)headers
                                  uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgress
                                downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgress
                                         success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
                                         failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure
{
    NSError *serializationError = nil;
    //序列化好一个请求
    NSMutableURLRequest *request = [self.requestSerializer requestWithMethod:method URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters error:&serializationError];
    //设置请求头
    for (NSString *headerField in headers.keyEnumerator) {
        [request setValue:headers[headerField] forHTTPHeaderField:headerField];
    }
    if (serializationError) {
        if (failure) {
            dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{
                failure(nil, serializationError);
            });
        }

        return nil;
    }

    __block NSURLSessionDataTask *dataTask = nil;
    //这里在AFURLSessionManager类再做详细分析
    dataTask = [self dataTaskWithRequest:request
                          uploadProgress:uploadProgress
                        downloadProgress:downloadProgress
                       completionHandler:^(NSURLResponse * __unused response, id responseObject, NSError *error) {
        if (error) {
            if (failure) {
                failure(dataTask, error);
            }
        } else {
            if (success) {
                success(dataTask, responseObject);
            }
        }
    }];

    return dataTask;
}

AFNetworking的单元测试中有归档解档的操作，这里实现NSSecureCoding和NSCopying协议，supportsSecureCoding返回YES，支持安全编码协议

#pragma mark - NSSecureCoding

+ (BOOL)supportsSecureCoding {
    return YES;
}

- (instancetype)initWithCoder:(NSCoder *)decoder {
    NSURL *baseURL = [decoder decodeObjectOfClass:[NSURL class] forKey:NSStringFromSelector(@selector(baseURL))];
    NSURLSessionConfiguration *configuration = [decoder decodeObjectOfClass:[NSURLSessionConfiguration class] forKey:@"sessionConfiguration"];
    if (!configuration) {
        NSString *configurationIdentifier = [decoder decodeObjectOfClass:[NSString class] forKey:@"identifier"];
        if (configurationIdentifier) {
            configuration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:configurationIdentifier];
        }
    }

    self = [self initWithBaseURL:baseURL sessionConfiguration:configuration];
    if (!self) {
        return nil;
    }

    self.requestSerializer = [decoder decodeObjectOfClass:[AFHTTPRequestSerializer class] forKey:NSStringFromSelector(@selector(requestSerializer))];
    self.responseSerializer = [decoder decodeObjectOfClass:[AFHTTPResponseSerializer class] forKey:NSStringFromSelector(@selector(responseSerializer))];
    AFSecurityPolicy *decodedPolicy = [decoder decodeObjectOfClass:[AFSecurityPolicy class] forKey:NSStringFromSelector(@selector(securityPolicy))];
    if (decodedPolicy) {
        self.securityPolicy = decodedPolicy;
    }

    return self;
}

- (void)encodeWithCoder:(NSCoder *)coder {
    [super encodeWithCoder:coder];

    [coder encodeObject:self.baseURL forKey:NSStringFromSelector(@selector(baseURL))];
    if ([self.session.configuration conformsToProtocol:@protocol(NSCoding)]) {
        [coder encodeObject:self.session.configuration forKey:@"sessionConfiguration"];
    } else {
        [coder encodeObject:self.session.configuration.identifier forKey:@"identifier"];
    }
    [coder encodeObject:self.requestSerializer forKey:NSStringFromSelector(@selector(requestSerializer))];
    [coder encodeObject:self.responseSerializer forKey:NSStringFromSelector(@selector(responseSerializer))];
    [coder encodeObject:self.securityPolicy forKey:NSStringFromSelector(@selector(securityPolicy))];
}

#pragma mark - NSCopying

- (instancetype)copyWithZone:(NSZone *)zone {
    AFHTTPSessionManager *HTTPClient = [[[self class] allocWithZone:zone] initWithBaseURL:self.baseURL sessionConfiguration:self.session.configuration];

    HTTPClient.requestSerializer = [self.requestSerializer copyWithZone:zone];
    HTTPClient.responseSerializer = [self.responseSerializer copyWithZone:zone];
    HTTPClient.securityPolicy = [self.securityPolicy copyWithZone:zone];
    return HTTPClient;
}