2 File: CacheStoragePolicy.m
3 Abstract: A function to determine the cache storage policy for a request.
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48 #import "CacheStoragePolicy.h"
50 extern NSURLCacheStoragePolicy CacheStoragePolicyForRequestAndResponse(NSURLRequest * request, NSHTTPURLResponse * response)
51 // See comment in header.
54 NSURLCacheStoragePolicy result;
56 assert(request != NULL);
57 assert(response != NULL);
59 // First determine if the request is cacheable based on its status code.
61 switch ([response statusCode]) {
76 // If the response might be cacheable, look at the "Cache-Control" header in
79 // IMPORTANT: We can't rely on -rangeOfString: returning valid results if the target
80 // string is nil, so we have to explicitly test for nil in the following two cases.
83 NSString * responseHeader;
85 responseHeader = [[response allHeaderFields][@"Cache-Control"] lowercaseString];
86 if ( (responseHeader != nil) && [responseHeader rangeOfString:@"no-store"].location != NSNotFound) {
91 // If we still think it might be cacheable, look at the "Cache-Control" header in
95 NSString * requestHeader;
97 requestHeader = [[request allHTTPHeaderFields][@"Cache-Control"] lowercaseString];
98 if ( (requestHeader != nil)
99 && ([requestHeader rangeOfString:@"no-store"].location != NSNotFound)
100 && ([requestHeader rangeOfString:@"no-cache"].location != NSNotFound) ) {
105 // Use the cacheable flag to determine the result.
109 // This code only caches HTTPS data in memory. This is inline with earlier versions of
110 // iOS. Modern versions of iOS use file protection to protect the cache, and thus are
111 // happy to cache HTTPS on disk. I've not made the correspondencing change because
112 // it's nice to see all three cache policies in action.
114 if ([[[[request URL] scheme] lowercaseString] isEqual:@"https"]) {
115 result = NSURLCacheStorageAllowedInMemoryOnly;
117 result = NSURLCacheStorageAllowed;
120 result = NSURLCacheStorageNotAllowed;