AFNetworking源码探究（九） —— AFURLSess
2018-03-01 本文已影响39人
刀客传奇
版本记录
| 版本号 | 时间 |
|---|---|
| V1.0 | 2018.03.01 |
前言
我们做APP发起网络请求，都离不开一个非常有用的框架AFNetworking，可以说这个框架的知名度已经超过了苹果的底层网络请求部分，很多人可能不知道苹果底层是如何发起网络请求的，但是一定知道
AFNetworking，接下来几篇我们就一起详细的解析一下这个框架。感兴趣的可以看上面写的几篇。
1. AFNetworking源码探究（一） —— 基本介绍
2. AFNetworking源码探究（二） —— GET请求实现之NSURLSessionDataTask实例化（一）
3. AFNetworking源码探究（三） —— GET请求实现之任务进度设置和通知监听（一）
4. AFNetworking源码探究（四） —— GET请求实现之代理转发思想（一）
5. AFNetworking源码探究（五） —— AFURLSessionManager中NSURLSessionDelegate详细解析（一）
6. AFNetworking源码探究（六） —— AFURLSessionManager中NSURLSessionTaskDelegate详细解析（一）
7. AFNetworking源码探究（七） —— AFURLSessionManager中NSURLSessionDataDelegate详细解析（一）
8. AFNetworking源码探究（八） —— AFURLSessionManager中NSURLSessionDownloadDelegate详细解析（一）
回顾
上面一篇，主要讲述了代理NSURLSessionDownloadDelegate中的三个方法，这一篇我们就看一下AFN自定义代理AFURLSessionManagerTaskDelegate中三个代理转发的实现。
1. - (void)URLSession:(__unused NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
先看一下该自定义代理方法的实现。
- (void)URLSession:(__unused NSURLSession *)session
task:(NSURLSessionTask *)task
didCompleteWithError:(NSError *)error
{
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wgnu"
__strong AFURLSessionManager *manager = self.manager;
__block id responseObject = nil;
__block NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
userInfo[AFNetworkingTaskDidCompleteResponseSerializerKey] = manager.responseSerializer;
//Performance Improvement from #2672
NSData *data = nil;
if (self.mutableData) {
data = [self.mutableData copy];
//We no longer need the reference, so nil it out to gain back some memory.
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];
});
});
});
}
#pragma clang diagnostic pop
}
这里有几点需要注意：
(a) userInfo参数
这个参数是一个可变字典。
NSString * const AFNetworkingTaskDidCompleteResponseSerializerKey = @"com.alamofire.networking.task.complete.responseserializer";
__block NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
userInfo[AFNetworkingTaskDidCompleteResponseSerializerKey] = manager.responseSerializer;
这个userInfo用来存储一些相关信息，存储responseSerializer响应解析对象。
(b) 释放mutableData内存
这一段代码需要我们学习。
//Performance Improvement from #2672
NSData *data = nil;
if (self.mutableData) {
data = [self.mutableData copy];
//We no longer need the reference, so nil it out to gain back some memory.
self.mutableData = nil;
}
当我们不用self.mutableData这个对象的时候，就设置为nil，节省内存，数据通过data传出去了。
(c) 有错误error不为空
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];
});
});
}
有错误的话，就按照上面的逻辑进行处理。
首先就是更新userInfo信息
NSString * const AFNetworkingTaskDidCompleteErrorKey = @"com.alamofire.networking.task.complete.error";
userInfo[AFNetworkingTaskDidCompleteErrorKey] = error;
然后就是在主线程进行block回调，并发出了一个通知AFNetworkingTaskDidCompleteNotification。
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];
});
});
(d) 无错误
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];
});
});
});
}
上面就是无错误时的处理工作：
- 首先我们注意下队列，是在一个并行队列执行的。
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;
}
无错误时候的处理，都是在这个队列中进行处理的。
- 解析数据
NSError *serializationError = nil;
responseObject = [manager.responseSerializer responseObjectForResponse:task.response data:data error:&serializationError];
- (id)responseObjectForResponse:(NSURLResponse *)response
data:(NSData *)data
error:(NSError *__autoreleasing *)error
{
[self validateResponse:(NSHTTPURLResponse *)response data:data error:error];
return data;
}
- (BOOL)validateResponse:(NSHTTPURLResponse *)response
data:(NSData *)data
error:(NSError * __autoreleasing *)error
{
BOOL responseIsValid = YES;
NSError *validationError = nil;
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]) {
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;
}
大家看一下，这里还验证了response的有效性，具体怎么验证后面会分篇进行说明。
- 如果是下载文件，那么
responseObject为下载的路径
if (self.downloadFileURL) {
responseObject = self.downloadFileURL;
}
写入userInfo
if (responseObject) {
userInfo[AFNetworkingTaskDidCompleteSerializedResponseKey] = responseObject;
}
如果解析response有错误，就更新userInfo
if (serializationError) {
userInfo[AFNetworkingTaskDidCompleteErrorKey] = serializationError;
}
- 结果的回调
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];
});
});
在下面的队列组中进行完成的处理
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;
}
这里其实就结果的回调self.completionHandler(task.response, responseObject, serializationError)，并发出通知，name为NSString * const AFNetworkingTaskDidCompleteNotification = @"com.alamofire.networking.task.complete";。
2. - (void)URLSession:(__unused NSURLSession *)session dataTask:(__unused NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data
- (void)URLSession:(__unused NSURLSession *)session
dataTask:(__unused NSURLSessionDataTask *)dataTask
didReceiveData:(NSData *)data
{
[self.mutableData appendData:data];
}
这个很好理解，其实就是周期性的调用，在这个方法里面拼接了数据。
3. - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location
下载成功了被NSURLSession代理转发到这里
- (void)URLSession:(NSURLSession *)session
downloadTask:(NSURLSessionDownloadTask *)downloadTask
didFinishDownloadingToURL:(NSURL *)location
{
NSError *fileManagerError = nil;
self.downloadFileURL = nil;
if (self.downloadTaskDidFinishDownloading) {
self.downloadFileURL = self.downloadTaskDidFinishDownloading(session, downloadTask, location);
if (self.downloadFileURL) {
[[NSFileManager defaultManager] moveItemAtURL:location toURL:self.downloadFileURL error:&fileManagerError];
if (fileManagerError) {
[[NSNotificationCenter defaultCenter] postNotificationName:AFURLSessionDownloadTaskDidFailToMoveFileNotification object:downloadTask userInfo:fileManagerError.userInfo];
}
}
}
}
这个大家是否注意到以前那个转发到这里的NSURLSession的代理方法，里面也有关于路径的处理，这里也进行了处理，两处都处理了，为什么呢？
转发前的NSURLSession代理的下载路径是所有request公用的下载路径，一旦设置，所有的request都会下载到之前那个路径。而这个是对应的每个task的，每个task可以设置各自下载路径。
后记
本篇解析的就是
AFURLSessionManagerTaskDelegate代理中实现的三个方法。喜欢的点个赞~~~
