我有一个应该很常见的用例，但我找不到使用 AFNetworking 处理它的简单方法：
每当服务器为任何请求返回特定状态代码时，我都想：
我认为这可以通过一些全局完成/错误处理程序来完成AFHTTPClient，但我没有发现任何有用的东西。那么，做我想做的事的“正确”方法是什么？enqueueHTTPRequestOperation:在我的子类中覆盖AFHTTPClient，复制操作并用我想要的块包装原始完成处理程序（重新验证，排队复制操作）？还是我完全走错了路？
谢谢！
编辑：删除了对 401 状态代码的引用，因为这可能是在我使用令牌身份验证时为 HTTP 基本保留的。
我使用另一种方法通过 AFNetworking 2.0 执行此操作。
您可以dataTaskWithRequest:success:failure:对传递的完成块进行子类化和包装，并进行一些错误检查。例如，如果您使用 OAuth，您可以观察 401 错误（到期）并刷新您的访问令牌。
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)urlRequest completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))originalCompletionHandler{
//create a completion block that wraps the original
void (^authFailBlock)(NSURLResponse *response, id responseObject, NSError *error) = ^(NSURLResponse *response, id responseObject, NSError *error)
{
NSHTTPURLResponse* httpResponse = (NSHTTPURLResponse*)response;
if([httpResponse statusCode] == 401){
NSLog(@"401 auth error!");
//since there was an error, call you refresh method and then redo the original task
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
//call your method for refreshing OAuth tokens. This is an example:
[self refreshAccessToken:^(id responseObject) {
NSLog(@"response was %@", responseObject);
//store your new token
//now, queue up and execute the original task
NSURLSessionDataTask *originalTask = [super dataTaskWithRequest:urlRequest completionHandler:originalCompletionHandler];
[originalTask resume];
}];
});
}else{
NSLog(@"no auth error");
originalCompletionHandler(response, responseObject, error);
}
};
NSURLSessionDataTask *task = [super dataTaskWithRequest:urlRequest completionHandler:authFailBlock];
return task;
}
在 AFHTTPClient 的 init 方法中注册AFNetworkingOperationDidFinishNotification将在请求完成后发布的。
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(HTTPOperationDidFinish:) name:AFNetworkingOperationDidFinishNotification object:nil];
在通知处理程序中检查状态代码并创建一个新的copy。AFHTTPRequestOperation
- (void)HTTPOperationDidFinish:(NSNotification *)notification {
AFHTTPRequestOperation *operation = (AFHTTPRequestOperation *)[notification object];
if (![operation isKindOfClass:[AFHTTPRequestOperation class]]) {
return;
}
if ([operation.response statusCode] == 401) {
// enqueue a new request operation here
}
}
编辑：
一般来说，您不需要这样做，只需使用此 AFNetworking 方法处理身份验证：
- (void)setAuthenticationChallengeBlock:(void (^)(NSURLConnection *connection, NSURLAuthenticationChallenge *challenge))block;
这是用户 @adamup 的答案的Swift实现
class SessionManager:AFHTTPSessionManager{
static let sharedInstance = SessionManager()
override func dataTaskWithRequest(request: NSURLRequest!, completionHandler: ((NSURLResponse!, AnyObject!, NSError!) -> Void)!) -> NSURLSessionDataTask! {
var authFailBlock : (response:NSURLResponse!, responseObject:AnyObject!, error:NSError!) -> Void = {(response:NSURLResponse!, responseObject:AnyObject!, error:NSError!) -> Void in
var httpResponse = response as! NSHTTPURLResponse
if httpResponse.statusCode == 401 {
//println("auth failed")
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), { () -> Void in
self.refreshToken(){ token -> Void in
if let tkn = token{
var mutableRequest = request.mutableCopy() as! NSMutableURLRequest
mutableRequest.setValue(tkn, forHTTPHeaderField: "Authorization")
var newRequest = mutableRequest.copy() as! NSURLRequest
var originalTask = super.dataTaskWithRequest(newRequest, completionHandler: completionHandler)
originalTask.resume()
}else{
completionHandler(response,responseObject,error)
}
}
})
}
else{
//println("no auth error")
completionHandler(response,responseObject,error)
}
}
var task = super.dataTaskWithRequest(request, completionHandler:authFailBlock )
return task
}}
其中 refreshToken (...) 是我为从服务器获取新令牌而编写的扩展方法。
采取了类似的方法，但我无法通过 phix23 的回答获得状态代码对象，因此我需要一个不同的行动计划。AFNetworking 2.0 改变了一些事情。
-(void)networkRequestDidFinish: (NSNotification *) notification
{
NSError *error = [notification.userInfo objectForKey:AFNetworkingTaskDidCompleteErrorKey];
NSHTTPURLResponse *httpResponse = error.userInfo[AFNetworkingOperationFailingURLResponseErrorKey];
if (httpResponse.statusCode == 401){
NSLog(@"Error was 401");
}
}
如果您是子类化AFHTTPSessionManager或直接使用 anAFURLSessionManager您可以使用以下方法设置任务完成后执行的块：
/**
Sets a block to be executed as the last message related to a specific task, as handled by the `NSURLSessionTaskDelegate` method `URLSession:task:didCompleteWithError:`.
@param block A block object to be executed when a session task is completed. The block has no return value, and takes three arguments: the session, the task, and any error that occurred in the process of executing the task.
*/
- (void)setTaskDidCompleteBlock:(void (^)(NSURLSession *session, NSURLSessionTask *task, NSError *error))block;
只需为其中的会话的每个任务执行您想做的任何事情：
[self setTaskDidCompleteBlock:^(NSURLSession *session, NSURLSessionTask *task, NSError *error) {
if ([task.response isKindOfClass:[NSHTTPURLResponse class]]) {
NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)task.response;
if (httpResponse.statusCode == 500) {
}
}
}];
编辑：
事实上，如果您需要处理响应对象中返回的错误，上述方法将无法完成这项工作。如果您要进行子类化，一种方法AFHTTPSessionManager可能是子类化并设置一个自定义响应序列化程序，它的responseObjectForResponse:data:error:重载如下：
@interface MyJSONResponseSerializer : AFJSONResponseSerializer
@end
@implementation MyJSONResponseSerializer
#pragma mark - AFURLResponseSerialization
- (id)responseObjectForResponse:(NSURLResponse *)response
data:(NSData *)data
error:(NSError *__autoreleasing *)error
{
id responseObject = [super responseObjectForResponse:response data:data error:error];
if ([responseObject isKindOfClass:[NSDictionary class]]
&& /* .. check for status or error fields .. */)
{
// Handle error globally here
}
return responseObject;
}
@end
并将其设置在您的AFHTTPSessionManager子类中：
@interface MyAPIClient : AFHTTPSessionManager
+ (instancetype)sharedClient;
@end
@implementation MyAPIClient
+ (instancetype)sharedClient {
static MyAPIClient *_sharedClient = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_sharedClient = [[MyAPIClient alloc] initWithBaseURL:[NSURL URLWithString:MyAPIBaseURLString]];
_sharedClient.responseSerializer = [MyJSONResponseSerializer serializer];
});
return _sharedClient;
}
@end
为确保不会同时发出多个令牌刷新，最好将网络请求排队并在令牌刷新时阻塞队列，或者在令牌刷新方法中添加互斥锁（@synchronized 指令）。