Alamofire - NSURLCache is not working? - swift

Question

I set my cache as below
var cacheSizeMemory = 20 * 1024 * 1024
var cacheSizeDisk = 100 * 1024 * 1024
var sharedCache = NSURLCache(memoryCapacity: cacheSizeMemory, diskCapacity: cacheSizeDisk, diskPath: "SOME_PATH")
NSURLCache.setSharedURLCache(sharedCache)
Create request with cache policy
var request = NSMutableURLRequest(URL: NSURL(string: "\(baseUrl!)\(path)")!, cachePolicy: .ReturnCacheDataElseLoad, timeoutInterval: timeout)
Make a request and get a response with following Cache-Control private, max-age=60
Then try to check the cache
var cachedResponse = NSURLCache.sharedURLCache().cachedResponseForRequest(urlRequest)
value is nil
Any thoughts?

Answer 1

I was able to manually cache pages by writing them to the sharedURLCache like this:
Alamofire.request(req)
.response {(request, res, data, error) in
let cachedURLResponse = NSCachedURLResponse(response: res!, data: (data as NSData), userInfo: nil, storagePolicy: .Allowed)
NSURLCache.sharedURLCache().storeCachedResponse(cachedURLResponse, forRequest: request)
}
NSURLCache seems to respect the headers sent by the server, even if you configure the opposite everywhere else in your code.
The Wikipedia API, for example, sends
Cache-control: private, must-revalidate, max-age=0
Which translates to: Must revalidate after 0 seconds.
So NSURLCache says: “OK, I won’t cache anything.”
But by manually saving the response to the cache, it works. At least on iOS 8.2.
Almost lost my mind on this one. :)

Answer 2

I ended up manually adding Cache-Control as private in the header of my request and it now works. Don't even need to manually check the cache, Alamofire does it for you
let cachePolicy: NSURLRequestCachePolicy = isReachable() ? .ReloadIgnoringLocalCacheData : .ReturnCacheDataElseLoad
var request = NSMutableURLRequest(URL: NSURL(string: "\(baseUrl!)\(path)")!, cachePolicy: cachePolicy, timeoutInterval: timeout)
request.addValue("private", forHTTPHeaderField: "Cache-Control")
var alamoRequest = Manager.sharedInstance.request(urlRequest)

Answer 3

I found that URLCache does not save responses bigger than 5% (1/20) of capacity.
Default cache has memoryCapacity = 512000, it does not save to memory responses greater than 25600.
As a solution extend capacity

Answer 4

[Swift solution for resolving expiration of NSURLcache]
I think that main problem here is this: ReturnCacheDataElseLoad.
#arayax gave you the answer that will fix that probably, but my solution would be something like this:
Since I'm using Alamofire for Network requests I've set my configuration:
configuration.requestCachePolicy = .ReturnCacheDataElseLoad
And when I make request I do check internet connectivity, if it is true, then clear NSURLCache, so it will force Alamofire to make request on server and not from cache:
if Reachability.isConnectedToNetwork() == true {
ConfigService.cache.removeAllCachedResponses()
}
ConfigService.manager?.request(.GET, ...
I hope this will help, maybe for other type of problems with NSURLCache :)

Answer 5

For me it was Pragma →no-cache after removing this everything worked.

Answer 6

This is how I got the cache to work with Alamofire 4 and swift 3 (Semi full function for reference):
func getTheList(courseId : String )-> Void{
appConstants.sharedInstance.startLoading()
let TheURL = DEFAULT_APP_URL + "api/getMyList?Id="+ID
let urlString = NSURL(string: TheURL)
var mutableURLRequest = URLRequest(url: urlString! as URL)
mutableURLRequest.httpMethod = "GET"
mutableURLRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
mutableURLRequest.cachePolicy = NSURLRequest.CachePolicy.returnCacheDataElseLoad
Alamofire.request(mutableURLRequest)
.responseJSON
{.......