iOS Run two asynchronous method if failed - ios

Question

I have a scenario where I need to quiet refresh auth token (relogin) again if it expired when I accessing other API but I'm having a hard time thinking how to code this without creating redundant codes for every APIs even though the flow is similar.
When user has expired auth token > call paid API A (return 401 unauthorised) > relogin again > call paid API A (run successfully)
I'm having difficult in wrapping my mind to call paid API A the second time with less code and not falling into infinite loop trap. Is there any method useful for this case like NSNotification center?
Note: I need to use API in this format from AFNetworkinglogin
- (NSURLSessionDataTask *)getApiA:(CallbackBlock)block{
CallbackBlock _block = [block copy];
NSString *urlString = [[NSURL URLWithString:GET_API_A_URL relativeToURL:[NSURL URLWithString:HOME_URL]] absoluteString];
return [self GET:urlString parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
NSDictionary *response = (NSDictionary *)responseObject;
BLOCK_SAFE_RUN(block, response, nil, task);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
if([self unauthorizedAccess:task]){ //401
***//call Login once again > run getApiA again***
}else if ([self forbiddenAccess:task]){ //403
}
BLOCK_SAFE_RUN(block, nil, error, task);
}];
}

Answer 1

If i get it right you could split it into 2 methods. And pass a bool for trying again. e.g.:
- (NSURLSessionDataTask *)getApiA:(id)block {
NSString *urlString = [[NSURL URLWithString:GET_API_A_URL relativeToURL:[NSURL URLWithString:HOME_URL]] absoluteString];
return [self doApiACallWithURL:urlString firstTry:YES completion:block];
}
- (NSURLSessionDataTask *)doApiACallWithURL:(NSString *)url firstTry:(BOOL)first completion:(CallbackBlock)completion {
__weak typeof(self) wself = self;
return [self GET:urlString parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
NSDictionary *response = (NSDictionary *)responseObject;
BLOCK_SAFE_RUN(block, response, nil, task);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
if ([wself unauthorizedAccess:task]) { //401
if (first) {
[wself doApiACallWithURL:url firstTry:NO completion:completion];
}
} else if ([wself forbiddenAccess:task]) { //403
}
BLOCK_SAFE_RUN(block, nil, error, task);
}];
}
and use a weak self for blocks is in most cases a good idea.