Did iOS 8 break NSURLCache?

Question

Long story short, I just updated to Xcode 6 to check how my app works on iOS 8. I noticed that it doesn't use the cache even though it should. I'm using AFNetworking setting the cachePolicy like this:

sessionManager.requestSerializer.cachePolicy = NSURLRequestReturnCacheDataElseLoad;

I still have an iOS 7 device in which I tested the same code and it works there as expected.

Does anyone have a solution for this, or do we need to wait for Apple to fix it?

Answer 1

I'm almost certain that iOS 8.0 has broken NSURLSession's ability to cache HTTP response data. I've opened a radar with Apple about this issue.

Here's some sample code I wrote to prove this:

NSURLSession *session = [NSURLSession sharedSession];
NSURLCache *URLCache = [[NSURLCache alloc] initWithMemoryCapacity:4 * 1024 * 1024
                                                     diskCapacity:32 * 1024 * 1024
                                                         diskPath:nil];
[NSURLCache setSharedURLCache:URLCache];

dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
NSURL *URL = [NSURL URLWithString:@"http://i.imgur.com/b5pyONe.jpg"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL
                                         cachePolicy:NSURLRequestReturnCacheDataElseLoad
                                     timeoutInterval:5];
NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    if (error) {
        NSLog(@"Error occurred");
    } else {
        NSLog(@"Fetched resource!");
    }
    dispatch_semaphore_signal(semaphore);
}];
[task resume];

dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);

request = [NSURLRequest requestWithURL:URL
                           cachePolicy:NSURLRequestReturnCacheDataDontLoad
                       timeoutInterval:5];
task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    if (error) {
        NSLog(@"Something bad happened: %@", error);
    } else {
        NSLog(@"Fetched resource!");
    }
}];
[task resume];

Even creating your own NSURLSession -- with an NSURLSessionConfiguration that has an NSURLCache that you create yourself -- won't fix this issue. For now, if you need cached responses badly, you have to use NSURLConnection.