AFNetworking 源码阅读(v3.2.1)
2018-07-04 本文已影响75人
cdcyd
AFNetworking项目地址 https://github.com/AFNetworking/AFNetworking
下载打开后目录
AFNetworking
1.AFNetworking文件下是实现HTTP请求的类
2.UIKit+AFNetworking文件下是实现图片下载的类
下面我们主要看AFNetworking的HTTP请求实现，我们使用AF发送一个请求很简单，如下面的一个GET请求的例子
// 请求管理器
AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
// 参数JSON格式
manager.requestSerializer = [AFJSONRequestSerializer serializerWithWritingOptions:NSJSONWritingPrettyPrinted];
// 返回JSON格式
manager.responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];
// 超时时间
manager.requestSerializer.timeoutInterval = 30;
// 最大线程数
manager.operationQueue.maxConcurrentOperationCount = 5;
// 开始发送请求
[manager GET:@"url" parameters:nil progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id _Nullable responseObject) {
// 请求成功
} failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
// 请求失败
}];
上面涉及到了AFHTTPSessionManager、AFJSONRequestSerializer、AFJSONResponseSerializer几个类，下面我们就来挨个看他们都是干什么的
- AFJSONRequestSerializer：请求参数按JSON格式序列化，还有一个AFPropertyListRequestSerializer：请求参数按Plist格式序列化，它们都继承自AFHTTPRequestSerializer，而AFHTTPRequestSerializer的参数序列化格式是默认的普通的http的编码格式，即url?key1=value1&key2=value2，下面我们就来看一下AFHTTPRequestSerializer
@interface AFHTTPRequestSerializer : NSObject <AFURLRequestSerialization>
/// 返回参数编码的编码样式，默认为 NSUTF8StringEncoding
@property (nonatomic, assign) NSStringEncoding stringEncoding;
/// 是否可以通过手机网络发送请求
@property (nonatomic, assign) BOOL allowsCellularAccess;
/// 缓存策略
@property (nonatomic, assign) NSURLRequestCachePolicy cachePolicy;
/// 是否对cookies进行默认处理 默认为YES
@property (nonatomic, assign) BOOL HTTPShouldHandleCookies;
/// 是否可以在上个数据传输的请求完成后继续传输数据 默认为No
@property (nonatomic, assign) BOOL HTTPShouldUsePipelining;
/// 服务器的类型 默认为NSURLNetworkServiceTypeDefault
@property (nonatomic, assign) NSURLRequestNetworkServiceType networkServiceType;
/// 一个请求的超时时长 默认为60s
@property (nonatomic, assign) NSTimeInterval timeoutInterval;
/// 请求头的信息， 默认包含 Accept-Language 和 User-Agent
@property (readonly, nonatomic, strong) NSDictionary <NSString *, NSString *> *HTTPRequestHeaders;
/// 返回一个默认配置序列化对象
+ (instancetype)serializer;
/// 设置Header里面的字段，如果为field为空，那么这个字段会从Header里面移除
- (void)setValue:(nullable NSString *)value forHTTPHeaderField:(NSString *)field;
/// 根据key取出Hearder里面的值，返回字符串或者nil
- (nullable NSString *)valueForHTTPHeaderField:(NSString *)field;
/// 设置HTTP认证的用户名和密码
- (void)setAuthorizationHeaderFieldWithUsername:(NSString *)username password:(NSString *)password;
/// 移除验证的用户名和密码
- (void)clearAuthorizationHeader;
/// 将参数编码成一个查询字符串（默认包含：GET、DELETE、HEAD）
@property (nonatomic, strong) NSSet <NSString *> *HTTPMethodsEncodingParametersInURI;
/// 根据之前预定义的style设置查询字符串序列化的方法
- (void)setQueryStringSerializationWithStyle:(AFHTTPRequestQueryStringSerializationStyle)style;
/// 根据指定的block设置一个自定义查询字符序列化的方法。Block中传入一个request，编码的参数parameters和一个error，返回请求参数编码成一个查询字符串
- (void)setQueryStringSerializationWithBlock:(nullable NSString * (^)(NSURLRequest *request, id parameters, NSError * __autoreleasing *error))block;
/// 创建一个请求，根据传入的Method，如果为 `GET`、`HEAD`、`DELETE`，参数会拼接在Url的后面，否则参数会设置成HTTP的请求体，并根据request指定的parameterEncoding参数编码
- (NSMutableURLRequest *)requestWithMethod:(NSString *)method
URLString:(NSString *)URLString
parameters:(nullable id)parameters
error:(NSError * _Nullable __autoreleasing *)error;
/// 通过`AFMultipartFormData`类型的formData来构建请求体
- (NSMutableURLRequest *)multipartFormRequestWithMethod:(NSString *)method
URLString:(NSString *)URLString
parameters:(nullable NSDictionary <NSString *, id> *)parameters
constructingBodyWithBlock:(nullable void (^)(id <AFMultipartFormData> formData))block
error:(NSError * _Nullable __autoreleasing *)error;
/// 通过request创建一个request，新request的httpBody是`fileURL`指定的文件，并且是通过`HTTPBodyStream`这个属性添加，`HTTPBodyStream`属性的数据会自动添加为httpBody
- (NSMutableURLRequest *)requestWithMultipartFormRequest:(NSURLRequest *)request
writingStreamContentsToFile:(NSURL *)fileURL
completionHandler:(nullable void (^)(NSError * _Nullable error))handler;
@end
总结一下AFHTTPRequestSerializer，就是封装请求头信息，序列化请求参数
HTTP的头信息包括：请求方式、请求的URL 、HTTP的版本、Host、 Accept、 Cookie、 User-Agent、Accept-Language、Accept-Encoding、Connection等，其中有很多就是AF帮助我们构建的，下面贴出AFHTTPRequestSerializer的初始化方法
- (instancetype)init {
self = [super init];
if (!self) {
return nil;
}
// 编码方式
self.stringEncoding = NSUTF8StringEncoding;
// 存储HTTP头信息
self.mutableHTTPRequestHeaders = [NSMutableDictionary dictionary];
// 修改头信息的线程
self.requestHeaderModificationQueue = dispatch_queue_create("requestHeaderModificationQueue", DISPATCH_QUEUE_CONCURRENT);
// 构建Accept-Language信息
NSMutableArray *acceptLanguagesComponents = [NSMutableArray array];
[[NSLocale preferredLanguages] enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
float q = 1.0f - (idx * 0.1f);
[acceptLanguagesComponents addObject:[NSString stringWithFormat:@"%@;q=%0.1g", obj, q]];
*stop = q <= 0.5f;
}];
[self setValue:[acceptLanguagesComponents componentsJoinedByString:@", "] forHTTPHeaderField:@"Accept-Language"];
// 构建User-Agent信息（源码这里分类iOS、Watch、MAC三中，这里简化为iOS）
NSString *userAgent = [NSString stringWithFormat:@"%@/%@ (%@; iOS %@; Scale/%0.2f)", [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleExecutableKey] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleIdentifierKey], [[NSBundle mainBundle] infoDictionary][@"CFBundleShortVersionString"] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleVersionKey], [[UIDevice currentDevice] model], [[UIDevice currentDevice] systemVersion], [[UIScreen mainScreen] scale]];
if (![userAgent canBeConvertedToEncoding:NSASCIIStringEncoding]) {
NSMutableString *mutableUserAgent = [userAgent mutableCopy];
if (CFStringTransform((__bridge CFMutableStringRef)(mutableUserAgent), NULL, (__bridge CFStringRef)@"Any-Latin; Latin-ASCII; [:^ASCII:] Remove", false)) {
userAgent = mutableUserAgent;
}
}
[self setValue:userAgent forHTTPHeaderField:@"User-Agent"];
// 需要转换为查询字符串参数的请求类型 默认 "GET" "HEAD" "DELETE"
self.HTTPMethodsEncodingParametersInURI = [NSSet setWithObjects:@"GET", @"HEAD", @"DELETE", nil];
// 添加一些属性的KVC，包括allowsCellularAccess、cachePolicy、HTTPShouldHandleCookies、HTTPShouldUsePipelining、networkServiceType、timeoutInterval
self.mutableObservedChangedKeyPaths = [NSMutableSet set];
for (NSString *keyPath in AFHTTPRequestSerializerObservedKeyPaths()) {
if ([self respondsToSelector:NSSelectorFromString(keyPath)]) {
[self addObserver:self forKeyPath:keyPath options:NSKeyValueObservingOptionNew context:AFHTTPRequestSerializerObserverContext];
}
}
return self;
}
构建请求对象的方法有3个，如下截图
构建请求发放申明
下面贴出第一个方法的具体实现
- (NSMutableURLRequest *)requestWithMethod:(NSString *)method URLString:(NSString *)URLString parameters:(id)parameters error:(NSError *__autoreleasing *)error
{
NSParameterAssert(method);
NSParameterAssert(URLString);
// 基础url
NSURL *url = [NSURL URLWithString:URLString];
NSParameterAssert(url);
// 请求对象
NSMutableURLRequest *mutableRequest = [[NSMutableURLRequest alloc] initWithURL:url];
mutableRequest.HTTPMethod = method;
// 设置请求参数
for (NSString *keyPath in AFHTTPRequestSerializerObservedKeyPaths()) {
if ([self.mutableObservedChangedKeyPaths containsObject:keyPath]) {
[mutableRequest setValue:[self valueForKeyPath:keyPath] forKey:keyPath];
}
}
// AFURLRequestSerialization协议的方法，用于序列化参数，添加一些header信息
mutableRequest = [[self requestBySerializingRequest:mutableRequest withParameters:parameters error:error] mutableCopy];
return mutableRequest;
}
- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request withParameters:(id)parameters error:(NSError *__autoreleasing *)error
{
NSParameterAssert(request);
// 深拷贝一份请求对象
NSMutableURLRequest *mutableRequest = [request mutableCopy];
// 设置header信息
[self.HTTPRequestHeaders enumerateKeysAndObjectsUsingBlock:^(id field, id value, BOOL * __unused stop) {
if (![request valueForHTTPHeaderField:field]) {
[mutableRequest setValue:value forHTTPHeaderField:field];
}
}];
// 参数序列化
NSString *query = nil;
if (parameters) {
if (self.queryStringSerialization) {
NSError *serializationError;
query = self.queryStringSerialization(request, parameters, &serializationError);
if (serializationError) {
if (error) {
*error = serializationError;
}
return nil;
}
} else {
switch (self.queryStringSerializationStyle) {
case AFHTTPRequestQueryStringDefaultStyle:
query = AFQueryStringFromParameters(parameters);
break;
}
}
}
if ([self.HTTPMethodsEncodingParametersInURI containsObject:[[request HTTPMethod] uppercaseString]]) {
// 将参数转换为查询字符串并拼接到url后面，默认"GET" "HEAD" "DELETE"请求会走这里
if (query && query.length > 0) {
mutableRequest.URL = [NSURL URLWithString:[[mutableRequest.URL absoluteString] stringByAppendingFormat:mutableRequest.URL.query ? @"&%@" : @"?%@", query]];
}
} else {
// 其它请求将参数设置成HTTPBody，并且如果没有参数，则设置成""
if (!query) {
query = @"";
}
if (![mutableRequest valueForHTTPHeaderField:@"Content-Type"]) {
[mutableRequest setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
}
[mutableRequest setHTTPBody:[query dataUsingEncoding:self.stringEncoding]];
}
return mutableRequest;
}
到此，我们就构建NSURLRequest，其实它主要有两部分：构建头信息、处理参数
下面我们再来看一下返回信息AFJSONResponseSerializer
- AFJSONResponseSerializer：它主要用于对返回二进制数据NSData的解析，继承自AFHTTPResponseSerializer，其中的JSON表示它能解析的类型
- AFHTTPResponseSerializer：不做处理，直接返回NSData
- AFJSONResponseSerializer：JSON
- AFXMLParserResponseSerializer：xml
- AFXMLDocumentResponseSerializer：(Mac OS X) iPhone不能直接使用，需要用GData-XML
- AFPropertyListResponseSerializer：plist
- AFImageResponseSerializer：image
- AFCompoundResponseSerializer：多个组合，初始化时需要传入上面的一种或几种类型
它们都遵循AFURLResponseSerialization协议，下面贴出AFJSONResponseSerializer的实现方法
// AFURLResponseSerialization协议
- (id)responseObjectForResponse:(NSURLResponse *)response data:(NSData *)data error:(NSError *__autoreleasing *)error
{
// 判断返回的数据是否合法，如果不合法，直接返回nil
if (![self validateResponse:(NSHTTPURLResponse *)response data:data error:error]) {
if (!error || AFErrorOrUnderlyingErrorHasCodeInDomain(*error, NSURLErrorCannotDecodeContentData, AFURLResponseSerializationErrorDomain)) {
return nil;
}
}
// json解析
BOOL isSpace = [data isEqualToData:[NSData dataWithBytes:" " length:1]];
if (data.length == 0 || isSpace) {
return nil;
}
NSError *serializationError = nil;
id responseObject = [NSJSONSerialization JSONObjectWithData:data options:self.readingOptions error:&serializationError];
if (!responseObject)
{
// 解析失败，返回nil
if (error) {
*error = AFErrorWithUnderlyingError(serializationError, *error);
}
return nil;
}
// 是否需要移除nil值的key
if (self.removesKeysWithNullValues) {
return AFJSONObjectByRemovingKeysWithNullValues(responseObject, self.readingOptions);
}
return responseObject;
}
// 验证数据合法性函数
- (BOOL)validateResponse:(NSHTTPURLResponse *)response data:(NSData *)data error:(NSError * __autoreleasing *)error
{
// 是否合法
BOOL responseIsValid = YES;
// 错误信息
NSError *validationError = nil;
// 验证并生成错误信息
if (response && [response isKindOfClass:[NSHTTPURLResponse class]]) {
if (self.acceptableContentTypes && ![self.acceptableContentTypes containsObject:[response MIMEType]] && !([response MIMEType] == nil && [data length] == 0)) {
if ([data length] > 0 && [response URL]) {
NSString *desc = [NSString stringWithFormat:NSLocalizedStringFromTable(@"Request failed: unacceptable content-type: %@", @"AFNetworking", nil), [response MIMEType]];
NSMutableDictionary *mutableUserInfo = [@{NSLocalizedDescriptionKey:desc,
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]) {
NSString *desc = [NSString stringWithFormat:NSLocalizedStringFromTable(@"Request failed: %@ (%ld)", @"AFNetworking", nil), [NSHTTPURLResponse localizedStringForStatusCode:response.statusCode], (long)response.statusCode];
NSMutableDictionary *mutableUserInfo = [@{NSLocalizedDescriptionKey: desc,
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;
}
总结AFHTTPResponseSerializer及其子类，是处理NSURLResponse的，主要处理错误码、错误信息、解析返回的NSData等
- AFHTTPSessionManager：请求管理类，它继承自AFURLSessionManager，它主要封装了GET,POST,PUT,DELETE等等HTTPMehtod
@interface AFHTTPSessionManager : AFURLSessionManager <NSSecureCoding, NSCopying>
// 基础url
@property (readonly, nonatomic, strong, nullable) NSURL *baseURL;
// 请求x实体
@property (nonatomic, strong) AFHTTPRequestSerializer <AFURLRequestSerialization> * requestSerializer;
// 返回实体
@property (nonatomic, strong) AFHTTPResponseSerializer <AFURLResponseSerialization> * responseSerializer;
// SSL证书验证
@property (nonatomic, strong) AFSecurityPolicy *securityPolicy;
// 实例
+ (instancetype)manager;
// 通过url创建实例
- (instancetype)initWithBaseURL:(nullable NSURL *)url;
// 通过url和config创建实例
- (instancetype)initWithBaseURL:(nullable NSURL *)url
sessionConfiguration:(nullable NSURLSessionConfiguration *)configuration NS_DESIGNATED_INITIALIZER;
// 发起get请求
- (nullable NSURLSessionDataTask *)GET:(NSString *)URLString
parameters:(nullable id)parameters
success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure DEPRECATED_ATTRIBUTE;
// 发起get请求，带进度条
- (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;
// 发起head请求
- (nullable NSURLSessionDataTask *)HEAD:(NSString *)URLString
parameters:(nullable id)parameters
success:(nullable void (^)(NSURLSessionDataTask *task))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;
// 发起post请求
- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString
parameters:(nullable id)parameters
success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure DEPRECATED_ATTRIBUTE;
// 发起post请求，带进度条
- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString
parameters:(nullable id)parameters
progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgress
success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;
// 发起post请求，添加formdata，一般用于上传文件
- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString
parameters:(nullable id)parameters
constructingBodyWithBlock:(nullable void (^)(id <AFMultipartFormData> formData))block
success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure DEPRECATED_ATTRIBUTE;
// 发起post请求，添加formdata，一般用于上传文件，带进度条
- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString
parameters:(nullable id)parameters
constructingBodyWithBlock:(nullable void (^)(id <AFMultipartFormData> formData))block
progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgress
success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;
// 发起put请求
- (nullable NSURLSessionDataTask *)PUT:(NSString *)URLString
parameters:(nullable id)parameters
success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;
// 发起patch请求
- (nullable NSURLSessionDataTask *)PATCH:(NSString *)URLString
parameters:(nullable id)parameters
success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;
// 发起delete请求
- (nullable NSURLSessionDataTask *)DELETE:(NSString *)URLString
parameters:(nullable id)parameters
success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;
@end
它的实现最后都会汇集到下面两个方法中，一个上传，一个下载
- (NSURLSessionDataTask *)POST:(NSString *)URLString
parameters:(id)parameters
constructingBodyWithBlock:(void (^)(id <AFMultipartFormData> formData))block
progress:(nullable void (^)(NSProgress * _Nonnull))uploadProgress
success:(void (^)(NSURLSessionDataTask *task, id responseObject))success
failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure
{
// 构建请求实体
NSError *serializationError = nil;
NSMutableURLRequest *request = [self.requestSerializer multipartFormRequestWithMethod:@"POST" URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters constructingBodyWithBlock:block error:&serializationError];
if (serializationError) {
if (failure) {
dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{
failure(nil, serializationError);
});
}
return nil;
}
// 构建上传任务
__block NSURLSessionDataTask *task = [self uploadTaskWithStreamedRequest:request progress:uploadProgress completionHandler:^(NSURLResponse * __unused response, id responseObject, NSError *error) {
if (error) {
if (failure) {
failure(task, error);
}
} else {
if (success) {
success(task, responseObject);
}
}
}];
// 开始任务
[task resume];
return task;
}
- (NSURLSessionDataTask *)dataTaskWithHTTPMethod:(NSString *)method
URLString:(NSString *)URLString
parameters:(id)parameters
uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgress
downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgress
success:(void (^)(NSURLSessionDataTask *, id))success
failure:(void (^)(NSURLSessionDataTask *, NSError *))failure
{
// 构建请求体
NSError *serializationError = nil;
NSMutableURLRequest *request = [self.requestSerializer requestWithMethod:method URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters error:&serializationError];
if (serializationError) {
if (failure) {
dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{
failure(nil, serializationError);
});
}
return nil;
}
// 构建下载任务
__block NSURLSessionDataTask *dataTask = nil;
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;
}
从上面的方法中，我们可以看出都分为3步，构建请求体、构建下载/上传任务、开始任务
构建请求体：它由AFHTTPRequestSerializer完成
构建下载/上传任务：它主要由AFURLSessionManager完成
下面我们就来看一下AFURLSessionManager
- AFURLSessionManager：管理NSURLSession对象，下面是它的头文件注释
@interface AFURLSessionManager : NSObject <NSURLSessionDelegate, NSURLSessionTaskDelegate, NSURLSessionDataDelegate, NSURLSessionDownloadDelegate, NSSecureCoding, NSCopying>
// 会话
@property (readonly, nonatomic, strong) NSURLSession *session;
// NSURLSession的队列
@property (readonly, nonatomic, strong) NSOperationQueue *operationQueue;
// 序列化响应数据的对象
@property (nonatomic, strong) id <AFURLResponseSerialization> responseSerializer;
// 安全策略
@property (nonatomic, strong) AFSecurityPolicy *securityPolicy;
#if !TARGET_OS_WATCH
// 网络监控管理者
@property (readwrite, nonatomic, strong) AFNetworkReachabilityManager *reachabilityManager;
#endif
// 当前被管理的任务的集合（包括data upload download）
@property (readonly, nonatomic, strong) NSArray <NSURLSessionTask *> *tasks;
// 当前data的任务集合
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDataTask *> *dataTasks;
// 当前upload的任务集合
@property (readonly, nonatomic, strong) NSArray <NSURLSessionUploadTask *> *uploadTasks;
// 当前download的任务集合
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDownloadTask *> *downloadTasks;
// 回调的队列，如果为空，就在主队列
@property (nonatomic, strong, nullable) dispatch_queue_t completionQueue;
// block会在这个组中调用，如果为空，就使用一个私有的
@property (nonatomic, strong, nullable) dispatch_group_t completionGroup;
// 解决在后台创建上传任务返回nil的bug，默认为NO，如果设为YES，在后台创建上传任务失败会尝试重新创建该任务
@property (nonatomic, assign) BOOL attemptsToRecreateUploadTasksForBackgroundSessions;
// 初始化
- (instancetype)initWithSessionConfiguration:(nullable NSURLSessionConfiguration *)configuration NS_DESIGNATED_INITIALIZER;
// 是否取消未完成的任务来使session失效
// NSURLSession有两个方法：
// -(void)finishTasksAndInvalidate; 标示待完成所有的任务后失效
// -(void)invalidateAndCancel; 标示 立即失效，未完成的任务也将结束
- (void)invalidateSessionCancelingTasks:(BOOL)cancelPendingTasks;
// 下面2个是DataTask相关的方法，对应没有进度条和有进度条
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler DEPRECATED_ATTRIBUTE;
- (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;
/// 下面3个是UploadTask相关的方法，对应fileURL/data/request 这三种不同的数据源
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
fromFile:(NSURL *)fileURL
progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
fromData:(nullable NSData *)bodyData
progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;
- (NSURLSessionUploadTask *)uploadTaskWithStreamedRequest:(NSURLRequest *)request
progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;
// 下面2个是DownloadTask相关的方法
- (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request
progress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock
destination:(nullable NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
completionHandler:(nullable void (^)(NSURLResponse *response, NSURL * _Nullable filePath, NSError * _Nullable error))completionHandler;
- (NSURLSessionDownloadTask *)downloadTaskWithResumeData:(NSData *)resumeData
progress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock
destination:(nullable NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
completionHandler:(nullable void (^)(NSURLResponse *response, NSURL * _Nullable filePath, NSError * _Nullable error))completionHandler;
// 通过task获取其上传进度
- (nullable NSProgress *)uploadProgressForTask:(NSURLSessionTask *)task;
// 通过ytask获取其下载进度
- (nullable NSProgress *)downloadProgressForTask:(NSURLSessionTask *)task;
// 下面是一些代理和block回调的相关函数
- (void)setSessionDidBecomeInvalidBlock:(nullable void (^)(NSURLSession *session, NSError *error))block;
- (void)setSessionDidReceiveAuthenticationChallengeBlock:(nullable NSURLSessionAuthChallengeDisposition (^)(NSURLSession *session, NSURLAuthenticationChallenge *challenge, NSURLCredential * _Nullable __autoreleasing * _Nullable credential))block;
- (void)setTaskNeedNewBodyStreamBlock:(nullable NSInputStream * (^)(NSURLSession *session, NSURLSessionTask *task))block;
- (void)setTaskWillPerformHTTPRedirectionBlock:(nullable NSURLRequest * _Nullable (^)(NSURLSession *session, NSURLSessionTask *task, NSURLResponse *response, NSURLRequest *request))block;
- (void)setTaskDidReceiveAuthenticationChallengeBlock:(nullable NSURLSessionAuthChallengeDisposition (^)(NSURLSession *session, NSURLSessionTask *task, NSURLAuthenticationChallenge *challenge, NSURLCredential * _Nullable __autoreleasing * _Nullable credential))block;
- (void)setTaskDidSendBodyDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionTask *task, int64_t bytesSent, int64_t totalBytesSent, int64_t totalBytesExpectedToSend))block;
- (void)setTaskDidCompleteBlock:(nullable void (^)(NSURLSession *session, NSURLSessionTask *task, NSError * _Nullable error))block;
- (void)setDataTaskDidReceiveResponseBlock:(nullable NSURLSessionResponseDisposition (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSURLResponse *response))block;
- (void)setDataTaskDidBecomeDownloadTaskBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSURLSessionDownloadTask *downloadTask))block;
- (void)setDataTaskDidReceiveDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSData *data))block;
- (void)setDataTaskWillCacheResponseBlock:(nullable NSCachedURLResponse * (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSCachedURLResponse *proposedResponse))block;
- (void)setDidFinishEventsForBackgroundURLSessionBlock:(nullable void (^)(NSURLSession *session))block AF_API_UNAVAILABLE(macos);
- (void)setDownloadTaskDidFinishDownloadingBlock:(nullable NSURL * _Nullable (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, NSURL *location))block;
- (void)setDownloadTaskDidWriteDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, int64_t bytesWritten, int64_t totalBytesWritten, int64_t totalBytesExpectedToWrite))block;
- (void)setDownloadTaskDidResumeBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, int64_t fileOffset, int64_t expectedTotalBytes))block;
@end
从上可以知道，任务的创建有3种data(数据)、upload(上传)、download(下载)，它们的实现都很相似，这里从data来分析，下面是构建NSURLSessionDataTask的实现代码
- (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;
url_session_manager_create_task_safely(^{
// 通过NSURLSession创建NSURLSessionDataTask
// - (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request;
// - (NSURLSessionDataTask *)dataTaskWithURL:(NSURL *)url;
// - (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request fromFile:(NSURL *)fileURL;
// - (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request fromData:(NSData *)bodyData;
// - (NSURLSessionUploadTask *)uploadTaskWithStreamedRequest:(NSURLRequest *)request;
// - (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request;
// - (NSURLSessionDownloadTask *)downloadTaskWithURL:(NSURL *)url;
// - (NSURLSessionDownloadTask *)downloadTaskWithResumeData:(NSData *)resumeData;
// - (NSURLSessionStreamTask *)streamTaskWithHostName:(NSString *)hostname port:(NSInteger)port
// - (NSURLSessionStreamTask *)streamTaskWithNetService:(NSNetService *)service
dataTask = [self.session dataTaskWithRequest:request];
});
// 添加AFURLSessionManagerTaskDelegate代理
[self addDelegateForDataTask:dataTask uploadProgress:uploadProgressBlock downloadProgress:downloadProgressBlock completionHandler:completionHandler];
return dataTask;
}
上面的代码很简单，就是根据方法调用NSURLSession的相关方法创建相关的任务(data、upload、download)等，在添加AFURLSessionManagerTaskDelegate代理
第一步很好理解，就是创建任务，为什么要有第二步呢？为什么还有添加一个代理呢？
首先我们来看一下NSURLSession的代理，它有4个代理，在创建时只要设置一个相当于4个都设置了
self.session = [NSURLSession sessionWithConfiguration:self.sessionConfiguration
delegate:self
delegateQueue:self.operationQueue];
这里设置的代理后，就相对于设置了下面4个代理
1.NSURLSessionDelegate
URLSession:didBecomeInvalidWithError:
URLSession:didReceiveChallenge:completionHandler:
URLSessionDidFinishEventsForBackgroundURLSession:
2. NSURLSessionTaskDelegate
URLSession:willPerformHTTPRedirection:newRequest:completionHandler:
URLSession:task:didReceiveChallenge:completionHandler:
URLSession:task:didSendBodyData:totalBytesSent:totalBytesExpectedToSend:
URLSession:task:needNewBodyStream:
URLSession:task:didCompleteWithError:
3. NSURLSessionDataDelegate
URLSession:dataTask:didReceiveResponse:completionHandler:
URLSession:dataTask:didBecomeDownloadTask:
URLSession:dataTask:didReceiveData:
URLSession:dataTask:willCacheResponse:completionHandler:
4. NSURLSessionDownloadDelegate
URLSession:downloadTask:didFinishDownloadingToURL:
URLSession:downloadTask:didWriteData:totalBytesWritten:totalBytesWritten:totalBytesExpectedToWrite:
URLSession:downloadTask:didResumeAtOffset:expectedTotalBytes:
这里需要注意的是，这4个代理不一定都会走，它会根据Task的类型走，如DataTask才会走NSURLSessionDataDelegate，这里还有一个问题，就是当有多个任务同时进行时，我们不好区分到底是哪个人物的回调，当然我们可以通过比较dataTask，AFURLSessionManagerTaskDelegate代理就是为了解决这个问题的，我们就用DataTask类型来举例
- (void)addDelegateForDataTask:(NSURLSessionDataTask *)dataTask
uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgressBlock
downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgressBlock
completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
{
// 创建代理
AFURLSessionManagerTaskDelegate *delegate = [[AFURLSessionManagerTaskDelegate alloc] initWithTask:dataTask];
delegate.manager = self;
// 设置完成回调block
delegate.completionHandler = completionHandler;
// 任务描述
dataTask.taskDescription = self.taskDescriptionForSessionTasks;
// 存储task和delegate
[self setDelegate:delegate forTask:dataTask];
// 任务上传进度block
delegate.uploadProgressBlock = uploadProgressBlock;
// 任务下载进度block
delegate.downloadProgressBlock = downloadProgressBlock;
}
- (void)setDelegate:(AFURLSessionManagerTaskDelegate *)delegate
forTask:(NSURLSessionTask *)task
{
NSParameterAssert(task);
NSParameterAssert(delegate);
[self.lock lock];
self.mutableTaskDelegatesKeyedByTaskIdentifier[@(task.taskIdentifier)] = delegate;
[self addNotificationObserverForTask:task];
[self.lock unlock];
}
上面代码就是为每个task创建了一个代理，并且将完成、上传进度、下载进度的回调block赋值个代理，再将代理和任务存储到属性mutableTaskDelegatesKeyedByTaskIdentifier中，这样就使得每一个task都有它自己的代理，当task回调时，我们通过它找到delegate，再用delegate调用相关代理方法，然后再在代理方法中回调相关的block，具体实现如下
在NSURLSessionDataDelegate回调时，下面是获取数据完成的代理
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
// 获取任务对应的delegate
AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:task];
// 如果有delegate，则调用相关的代理方法
if (delegate) {
[delegate URLSession:session task:task didCompleteWithError:error];
// 这里任务完成了，移除任务和代理
[self removeDelegateForTask:task];
}
if (self.taskDidComplete) {
self.taskDidComplete(session, task, error);
}
}
再来看AFURLSessionManagerTaskDelegate代理中相关实现
- (void)URLSession:(__unused NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
__strong AFURLSessionManager *manager = self.manager;
__block id responseObject = nil;
__block NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
userInfo[AFNetworkingTaskDidCompleteResponseSerializerKey] = manager.responseSerializer;
NSData *data = nil;
if (self.mutableData) {
data = [self.mutableData copy];
self.mutableData = nil;
}
if (self.downloadFileURL) {
userInfo[AFNetworkingTaskDidCompleteAssetPathKey] = self.downloadFileURL;
} else if (data) {
userInfo[AFNetworkingTaskDidCompleteResponseDataKey] = data;
}
if (error) {
userInfo[AFNetworkingTaskDidCompleteErrorKey] = error;
dispatch_group_async(manager.completionGroup ?: url_session_manager_completion_group(), manager.completionQueue ?: dispatch_get_main_queue(), ^{
if (self.completionHandler) {
self.completionHandler(task.response, responseObject, error);
}
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidCompleteNotification object:task userInfo:userInfo];
});
});
} else {
dispatch_async(url_session_manager_processing_queue(), ^{
NSError *serializationError = nil;
responseObject = [manager.responseSerializer responseObjectForResponse:task.response data:data error:&serializationError];
if (self.downloadFileURL) {
responseObject = self.downloadFileURL;
}
if (responseObject) {
userInfo[AFNetworkingTaskDidCompleteSerializedResponseKey] = responseObject;
}
if (serializationError) {
userInfo[AFNetworkingTaskDidCompleteErrorKey] = serializationError;
}
dispatch_group_async(manager.completionGroup ?: url_session_manager_completion_group(), manager.completionQueue ?: dispatch_get_main_queue(), ^{
if (self.completionHandler) {
self.completionHandler(task.response, responseObject, serializationError);
}
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidCompleteNotification object:task userInfo:userInfo];
});
});
});
}
}
这样就实现每一个任务都有它自己单独的代理，完成后即进行回调，还有一个好处是，当任务完成时，就可以移除代理，这样可以打破block的循环引用，所以我们再AF的block中直接在self不会造成循环引用
下面在看一下SSL相关类AFSecurityPolicy
- AFSecurityPolicy：它是为了验证证书的，至于HTTP和HTTPS的区别，这个在百度上有很多文章，我这里主要看AFSecurityPolicy都有哪些功能
@interface AFSecurityPolicy : NSObject <NSSecureCoding, NSCopying>
// 返回SSL Pinning的类型
@property (readonly, nonatomic, assign) AFSSLPinningMode SSLPinningMode;
// 这个属性保存着所有的可用做校验的证书的集合
// AFNetworking默认会搜索工程中所有.cer的证书文件
// 如果想制定某些证书，可使用certificatesInBundle在目标路径下加载证书，然后调用policyWithPinningMode:withPinnedCertificates创建一个本类对象。
// 只要在证书集合中任何一个校验通过，evaluateServerTrust:forDomain: 就会返回true，即通过校验
@property (nonatomic, strong, nullable) NSSet <NSData *> *pinnedCertificates;
// 允许无效或过期的证书，默认是不允许
@property (nonatomic, assign) BOOL allowInvalidCertificates;
// 是否验证证书中的域名domain
@property (nonatomic, assign) BOOL validatesDomainName;
// 返回指定bundle中的证书
+ (NSSet <NSData *> *)certificatesInBundle:(NSBundle *)bundle;
// 默认的实例对象，默认的认证设置为：
// 1. 不允许无效或过期的证书
// 2. 验证domain名称
// 3. 不对证书和公钥进行验证
+ (instancetype)defaultPolicy;
+ (instancetype)policyWithPinningMode:(AFSSLPinningMode)pinningMode;
+ (instancetype)policyWithPinningMode:(AFSSLPinningMode)pinningMode withPinnedCertificates:(NSSet <NSData *> *)pinnedCertificates;
- (BOOL)evaluateServerTrust:(SecTrustRef)serverTrust
forDomain:(nullable NSString *)domain;
@end
- 还一个问题，就是线程安全问题，在AF中用了很多GCD函数来保证线程安全
下面函数是用来保证任务创建安全的，AF给出的解释是在iOS8.0以前，任务创建有线程安全问题，如果你适配8.0以后的话，就不会用它了
static dispatch_queue_t url_session_manager_creation_queue() {
static dispatch_queue_t af_url_session_manager_creation_queue;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
af_url_session_manager_creation_queue = dispatch_queue_create("com.alamofire.networking.session.manager.creation", DISPATCH_QUEUE_SERIAL);
});
return af_url_session_manager_creation_queue;
}
static void url_session_manager_create_task_safely(dispatch_block_t _Nonnull block) {
if (block != NULL) {
if (NSFoundationVersionNumber < NSFoundationVersionNumber_With_Fixed_5871104061079552_bug) {
// Fix of bug
// Open Radar:http://openradar.appspot.com/radar?id=5871104061079552 (status: Fixed in iOS8)
// Issue about:https://github.com/AFNetworking/AFNetworking/issues/2093
dispatch_sync(url_session_manager_creation_queue(), block);
} else {
block();
}
}
}
下面是处理代理回调的线程函数，它是并行队列，在多个回调同时触发时，可以同时处理，可以加快数据的处理速度
static dispatch_queue_t url_session_manager_processing_queue() {
static dispatch_queue_t af_url_session_manager_processing_queue;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
af_url_session_manager_processing_queue = dispatch_queue_create("com.alamofire.networking.session.manager.processing", DISPATCH_QUEUE_CONCURRENT);
});
return af_url_session_manager_processing_queue;
}
下面是完成时的回调队列，当completionGroup属性为nil时，默认就使用它
static dispatch_group_t url_session_manager_completion_group() {
static dispatch_group_t af_url_session_manager_completion_group;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
af_url_session_manager_completion_group = dispatch_group_create();
});
return af_url_session_manager_completion_group;
}
下面再贴出完成时回调的代码
if (error) {
userInfo[AFNetworkingTaskDidCompleteErrorKey] = error;
// 请求出错
dispatch_group_async(manager.completionGroup ?: url_session_manager_completion_group(), manager.completionQueue ?: dispatch_get_main_queue(), ^{
if (self.completionHandler) {
// 在completionQueue存在时，则completionQueue中回调，否则在主队列中回调
self.completionHandler(task.response, responseObject, error);
}
dispatch_async(dispatch_get_main_queue(), ^{
// 在主线程中发出任务完成通知
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidCompleteNotification object:task userInfo:userInfo];
});
});
} else {
// 请求成功
dispatch_async(url_session_manager_processing_queue(), ^{
// 子线程并行处理回调数据
NSError *serializationError = nil;
responseObject = [manager.responseSerializer responseObjectForResponse:task.response data:data error:&serializationError];
if (self.downloadFileURL) {
responseObject = self.downloadFileURL;
}
if (responseObject) {
userInfo[AFNetworkingTaskDidCompleteSerializedResponseKey] = responseObject;
}
if (serializationError) {
userInfo[AFNetworkingTaskDidCompleteErrorKey] = serializationError;
}
dispatch_group_async(manager.completionGroup ?: url_session_manager_completion_group(), manager.completionQueue ?: dispatch_get_main_queue(), ^{
// 处理完成后，在completionQueue存在时，则completionQueue中回调，否则在主队列中回调
if (self.completionHandler) {
self.completionHandler(task.response, responseObject, serializationError);
}
dispatch_async(dispatch_get_main_queue(), ^{
// 在主线程中发出任务完成通知
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidCompleteNotification object:task userInfo:userInfo];
});
});
});
}
从上面代码可以看出，在默认情况下，不论我们在哪个线程用AF做请求，它的回调永远是在主队列中
到此AFNetworking文件下的类就全部读完了，实际我读AF就是想了解，在请求时，AF到底都为我们做了什么，总结一下：
- 请求体NSURLRequest的封装，涉及到构建head信息、Request相关参数设置，请求参数序列化等
- 根据请求类型创建相关的任务NSURLSessionTask，涉及到任务回调，线程安全等
- 返回数据NSData的解析
- HTTPS的支持
这里只是简单的总结这4步，但是每一步的实现都不易，如果想深入了解的话还会涉及到更多的知识点，同时也体会到写一个优秀的网络框架实属不易！
