Centralized error handling for AFNetworking - ios

Question

I'm looking for a way to handle "generic" errors such as request timeouts or for when the connection goes offline.
Basically, I have multiple (singleton) subclasses of AFHTTPSessionManager where each one represents a client that handles requests to different servers. Each client is setup by overriding initWithBaseURL as recommended by the author of AFNetworking; this is where the request/response serializers as well as generic headers are set. Here's a sample client:
#implementation APIClient
+ (APIClient *)sharedClient {
static APIClient *sharedClient = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedClient = [[self alloc] initWithBaseURL:[NSURL URLWithString:#"baseurl.goes.here"]];
});
return sharedClient;
}
- (instancetype)initWithBaseURL:(NSURL *)url
{
self = [super initWithBaseURL:url];
if(self) {
// Setup goes here
self.requestSerializer = [AFHTTPRequestSerializer serializer];
self.requestSerializer.timeoutInterval = 20.0f;
self.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:#"text/plain", #"text/html", nil];
[AFNetworkActivityIndicatorManager sharedManager].enabled = YES;
[AFNetworkActivityLogger sharedLogger].level = AFLoggerLevelDebug;
[[AFNetworkActivityLogger sharedLogger] startLogging];
}
return self;
}
- (void)startPostRequestWithPath:(NSString *)path parameters:(NSDictionary *)parameters successBlock:(APISuccessBlock)success failureBlock:(APIFailureBlock)failure
{
[self POST:path parameters:parameters
success:^(NSURLSessionDataTask * _Nonnull task, id _Nonnull responseObject) {
success(responseObject);
} failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
if(isGenericError) {
// Do something generic here
}
else {
failure(error);
}
}];
}
Inside my model (e.g, Post), I have a static method that can be used by the view controller to fetch the data by passing its own success/failure blocks to the client. So it goes like this:
View Controller --> Model --> Client --> Model --> View Controller.
And here's the implementation of the model
#implementation Post
+ (void)fetchLatestPost:(void (^)(Post *parsedData, NSError *error))completion
{
[[APIClient sharedClient] startRequestWithPath:kIndexPath
parameters:nil
requestType:RequestTypePost
successBlock:^(id data) {
NSError *parsingError = nil;
Post *post = [[Index alloc] initWithDictionary:data error:&err];
completion(index, nil);
}
failureBlock:^(NSError *error) {
completion(nil, error);
}
];
}
When a view controller tries to fetch that Post and the request times out, I'd like to hide the contents of the screen and show a refresh button; this logic is implemented in my BaseViewController so that all view controllers can reuse it. The question is, how do I restart the SAME request when that button is clicked? Do note that a view controller can make multiple requests from different models with different method signatures. Any help would be greatly appreciated as I can't seem to figure this out at all.
I used to handle this using delegates, where the BaseViewController would implement the "generic" delegate methods. However, I've been trying to switch to blocks and while it does have its advantages, it doesn't allow me to make use of my BaseViewController since it's can't "override" the view controller's failure blocks.