AFNetworking：重试操作时访问完成处理程序 [英] AFNetworking: Access to completion handlers when retrying operation

问题描述

给出一些上下文：我正在尝试为身份验证错误（使用令牌身份验证，而不是基本身份）实现全局错误处理程序，它应该尝试重新进行身份验证，然后重复原始失败的请求（请参阅我之前的问题： AFNetworking：全局处理错误并重复请求）

To give some context: I'm trying to implement a global error handler for authentication errors (using token authentication, not basic), which should try to re-authenticate and then repeat the original failed request (see my previous question: AFNetworking: Handle error globally and repeat request)

当前的方法是注册 AFNetworkingOperationDidFinishNotification 的观察者，该观察者进行重新认证并且（如果auth成功）重复原始请求：

The current approach is to register an observer for the AFNetworkingOperationDidFinishNotification which does the re-authentication and (if auth succeeded) repeats the original request:

- (void)operationDidFinish:(NSNotification *)notification
{
    AFHTTPRequestOperation *operation = (AFHTTPRequestOperation *)[notification object];

    if(![operation isKindOfClass:[AFHTTPRequestOperation class]]) {
        return;
    }

    if(403 == [operation.response statusCode]) {
        // try to re-authenticate and repeat the original request
        [[UserManager sharedUserManager] authenticateWithCredentials...
            success:^{
                // repeat original request

                // AFHTTPRequestOperation *newOperation = [operation copy]; // copies too much stuff, eg. response (although the docs suggest otherwise)
                AFHTTPRequestOperation *newOperation = [[AFHTTPRequestOperation alloc] initWithRequest:operation.request];

                // PROBLEM 1: newOperation has no completion blocks. How to use the original success/failure blocks here?

                [self enqueueHTTPRequestOperation:newOperation];
            }
            failure:^(NSError *error) {
                // PROBLEM 2: How to invoke failure block of original operation?
            }
        ];
    }
}

然而，我偶然发现了一些关于完成块的问题请求操作：

However, I stumbled upon some issues regarding completion blocks of request operations:

• 重复原始请求时，我显然希望执行完成块。但是， AFHTTPRequestOperation 不会保留对传递的成功和失败块的引用（请参阅 setCompletionBlockWithSuccess：failure：）并复制 NSOperation 的 completionBlock 可能不是一个好主意，因为 AFURLConnectionOperation的文档州：

• When repeating the original request, I obviously want its completion blocks to be executed. However, AFHTTPRequestOperation does not retain references to the passed success and failure blocks (see setCompletionBlockWithSuccess:failure:) and copying NSOperation's completionBlock is probably not a good idea, as the documentation for AFURLConnectionOperation states:

操作副本不包括 completionBlock 。 completionBlock 经常会强烈捕获对 self 的引用，这可能会令人惊讶地指向原始复制时的操作。

Operation copies do not include completionBlock. completionBlock often strongly captures a reference to self, which, perhaps surprisingly, would otherwise point to the original operation when copied.

如果重新验证失败，我想调用原始请求的失败块。所以，再一次，我需要直接访问它。

In case the re-authentication fails, I want to call the original request's failure block. So, again, I'd need direct access to this.

我在这里遗漏了什么吗？任何替代方法的想法？我应该提交功能请求吗？

Am I missing something here? Any ideas for alternative approaches? Should I file a feature request?

推荐答案

我在 Art.sy 的投资组合应用。我最终的结论是创建了一个NSOperationQueue子类，它具有在失败后创建各种AFNetworking HTTP操作的副本的功能（并且在放弃之前每个URL最多执行三次。）

I've come up with this problem in Art.sy's portfolio app. My eventual conclusion was to create a NSOperationQueue subclass which had functions to create copies of various AFNetworking HTTP Operations once they failed (and to do this up to three times per URL before giving up.)

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