我预计在我将请求缓存策略设置为NSURLRequestReturnCacheDataDontLoad后,getPath：parameters：success：failure：在离线时将使用缓存数据成功.但是,即使缓存中有数据(我通过使用代码检查缓存进行验证),getPath也会在飞行模式下失败.
AFNetworking github中有一个帖子：https://github.com/AFNetworking/AFNetworking/issues/378但似乎根本没有解决这个问题. AFNetworking的作者只是指向Apple’s document,它说：
NSURLRequestReturnCacheDataDontLoad
Specifies that the existing cache
data should be used to satisfy a request,regardless of its age or
expiration date. If there is no existing data in the cache
corresponding to a URL load request,no attempt is made to load the
data from the originating source,and the load is considered to have
Failed. This constant specifies a behavior that is similar to an
“offline” mode.
正如Apple所说,NSURLRequestReturnCacheDataDontLoad完全是为离线模式设计的.
我在iOS6中测试,我用NSURLCache和SDURLCache测试,都有相同的结果.
请求失败,错误消息：
2012-12-22 03:11:18.988 Testapp[43692:907] error: Error
Domain=NSURLErrorDomain Code=-1009 “The Internet connection appears to
be offline.” UserInfo=0x211b87c0
{NSErrorFailingURLStringKey=http://Testapp.com/api/v1/photo/latest/,
NSErrorFailingURLKey=http://Testapp.com/api/v1/photo/latest/,
NSLocalizedDescription=The Internet connection appears to be offline.,
NSUnderlyingError=0x211b9720 “The Internet connection appears to be
offline.”}
解决方法
AFNetworking中存在一个完全针对此问题的讨论主题：https://github.com/AFNetworking/AFNetworking/issues/566
感谢guykogus关于这个问题的提示和实验.我在这个问题上度过了一个晚上！
总结的解决方法是从缓存中读取响应,而不是使用NSURLRequestReturnCacheDataDontLoad策略：
NSCachedURLResponse *cachedResponse = [[NSURLCache sharedURLCache] cachedResponseForRequest:request];
if (cachedResponse != nil &&
[[cachedResponse data] length] > 0)
{
// Get cached data
....
}
