How to clear old cache in AFNetworking? - json

Question

I'm using AFNetworking to get JSON data loaded like this which is working great.
SessionManager *sessionManager = [SessionManager sharedClient];
[sessionManager setResponseSerializer:[AFJSONResponseSerializer serializer]];
[sessionManager setRequestSerializer:[AFJSONRequestSerializer serializer]];
[sessionManager GET:urlString
parameters:nil
success:^(NSURLSessionDataTask *task, id responseObject) {
self.navigationItem.titleView = nil;
self.data = [responseObject objectForKey:#"courses"];
self.title = responseObject[#"meta"][#"ref_title"];
[self.tableView reloadData];
}
failure:^(NSURLSessionDataTask *task, NSError *error) {
NSString *errorString = [NSString stringWithFormat:#"%#",
[error localizedDescription]];
[aiView stopAnimating];
}];
The problem is that I don't want to be loading the data every time.
So I used
sessionManager.requestSerializer.cachePolicy = NSURLRequestReturnCacheDataElseLoad;
This allows faster user experience, but now the problem is that the data is never deleted, or is it? So the user might not realize there's newer data available.
For this I use at the moment NSTimer, which starts when app is loaded and then calls
[[NSURLCache sharedURLCache] removeAllCachedResponses];
I think this is pretty bad solution as the timer will call the method even if the data was loaded 5 seconds ago. So I ask is there anything better?
I've seen a similar question here, but it's about clearing image cache and there's nothing about the age of the cache. Best case for me would be if the cache could be deleted when the day changes.

Answer 1

Have you looked into other caching policies? NSURLRequestReloadRevalidatingCacheData looks like it might be more suitable for your needs. It will only use cache data if the origin source confirms that the data is still valid.

Answer 2

Well I decided to make a date check in application didFinishLaunchingWithOptions and saving the date to NSUserDefaults. So for me I set it so that if the dates don't match I clear all the cache and the stored values in NSUserDefaults.
If I understand the code correctly it should only clear everything if user launches the app on the next day, which is perfect for me.
NSDate *dateCheck = [NSDate date];
NSDate *saveDate = [[NSUserDefaults standardUserDefaults] objectForKey:#"lastStartDate"];
if (!saveDate) {
// This is the 1st run of the app
saveDate = [NSDate date];
[[NSUserDefaults standardUserDefaults] setObject:saveDate forKey:#"lastStartDate"];
}
NSLog(#"First run was on: %#", saveDate);
NSInteger interval = [[[NSCalendar currentCalendar] components:NSCalendarUnitDay
fromDate:saveDate
toDate:dateCheck
options:0] day];
if (interval < 0 || interval > 0) {
// Dates don't match lets remove cache and delete saveDate
[self removeAllCachedResponses];
NSString *appDomain = [[NSBundle mainBundle] bundleIdentifier];
[[NSUserDefaults standardUserDefaults] removePersistentDomainForName:appDomain];
} else {
// Dates are equal no need to do anything
NSLog(#"dates are same");
}
As you can see I delete everything from NSUserDefaults, as I'm not using it for anything else. You might want to change that for you.
EDIT:
Well day changed, so I decided to check if this actually works, and the answer is no. Here's my log
2014-09-10 16:00:30.626 SodexoMenuApp[4283:607] datecheck: 2014-09-10 21:00:30 +0000
2014-09-10 16:00:30.627 SodexoMenuApp[4283:607] First run was on: 2014-09-09 23:02:02 +0000
So something has to be changed. Any ideas?
EDIT 2:
I think I solved this. Just had to change components:NSCalendarUnitDay