Method calling itself with identical params - objective-c

Question

I have several "proxy" classes, which inherit from a "base proxy". These classes connect to my server and pass data to their delegates. In event of 0 status code, I want to handle these different requests in the same way.
For 0 status codes, I want to retry the method in 5 seconds, hoping the user's internet connection has improved.
SomethingProxy.m
- (void)fetchSomething {
NSString *fullPath = [NSString stringWithFormat:#"%#/route/index.json",MY_BASE_URL];
NSURL *url = [NSURL URLWithString:fullPath];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFJSONRequestOperation *operation = [[AFJSONRequestOperation alloc] initWithRequest:request];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
NSDictionary *d = (NSDictionary *)responseObject;
[self.delegate fetchedPolicy:d[#"keypath"]];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleOperationFailed:operation action:^{
[self fetchSomething];
}];
}];
NSOperationQueue *q = [[NSOperationQueue alloc] init]; [q addOperation:operation];
}
MyBaseProxy.m
- (bool)shouldRetryOperation:(AFHTTPRequestOperation *)o {
return self.retries < [self maxRetries];
}
- (void)handleOperationFailed:(AFHTTPRequestOperation *)o action:(ActionBlock)block {
NSInteger statusCode = o.response.statusCode;
if (statusCode == 0) {
if ([self shouldRetryOperation:o]) {
double delayInSeconds = 5.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
self.retries++;
block();
});
} else {
self.retries = 0;
[SVProgressHUD showErrorWithStatus:#"Please check your internet connection and try again"];
return;
}
}
self.retries = 0;
What's a better way to handle the request failure? Should I subclass AFHTTPRequestOperation?
EDIT: Removed confusing text. When I meant "same way", I meant per request Eg. handle all 500s the same, handle all 403s the same. I'm specifically asking for handling status code 0 - no internet connection.

Answer 1

The key situation you should be concerned with, IMHO, is when the network, itself, is not available to the device. In that case, you'd generally use Reachability to have a notification posted to your app when the network becomes available. No point in repeatedly retrying when (a) you know the network is unavailable; and (b) you easily can be notified when the network becomes available again.
If you're concerned about server-specific issues, I would be careful about send a request in 5 seconds. Let's say your server is overwhelmed and cannot respond to all the client requests. Having large numbers of clients proceeding to retry every 5 seconds might not improve the situation. It sort of depends upon why your server is not responding. You just want to make sure that the attempts to connect again will never make the situation worse.
(As an aside, the description for 403 says, "The server understood the request, but is refusing to fulfill it. Authorization will not help and the request SHOULD NOT be repeated.")
If you're going to employ a retry process, I'd specify some reasonable maximum number of retries (which, judging by your revised answer, you are doing). And perhaps you'd want something that when the app returns to foreground, you reinitiate your "retry three times, once every 15 seconds" logic (or whatever you settle upon). The scenario I'm thinking about is "user started app, it failed after exceeding max retries, and hit the home button on their device, and a few minutes/hours later, they tap on the app again (which might still be running)."