iOS 8是否打破了NSURLCache？

问题描述：

长话短说，我刚刚更新到Xcode 6来检查我的应用程序在iOS 8上是如何工作的。我注意到它不使用缓存，即使它应该。我正在使用AFNetworking设置cachePolicy，如下所示：

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;

我还有一个iOS 7设备，我在其中测试了相同的代码，它按预期工作。

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

有没有人有这方面的解决方案，还是我们需要等待Apple修复它？

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

答

我几乎可以肯定iOS 8.0已经破解了 NSURLSession 缓存HTTP响应数据的能力。我已经向Apple公开了关于这个问题的雷达。

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.

这里是我编写的一些示例代码来证明这一点：

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];

甚至创建自己的 NSURLSession - 您自己创建的 NSURLSessionConfiguration 具有 NSURLCache - 将无法解决此问题。现在，如果您需要严重缓存响应，则必须使用 NSURLConnection 。

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.

iOS 8是否打破了NSURLCache？

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