Fix SDURLCache with iOS 5+ (fix #30, #29)

- Disable SDURLCache at runtime if iOS version is >5 as this version
  now includes disk caching support
- Exchange category with a wrapper to add NSCoder protocol support
  to NSCachedURLResponse

Author: Olivier Poitrey

SDCachedURLResponse.h

@@ -0,0 +1,17 @@
+//
+//  SDCachedURLResponse.h
+//  SDURLCache
+//
+//  Created by Olivier Poitrey on 12/05/12.
+//  Copyright (c) 2012 Dailymotion. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@interface SDCachedURLResponse : NSObject <NSCoding, NSCopying>
+
+@property (nonatomic, retain) NSCachedURLResponse *response;
+
++ (id)cachedURLResponseWithNSCachedURLResponse:(NSCachedURLResponse *)response;
+
+@end

SDCachedURLResponse.m

@@ -0,0 +1,65 @@
+//
+//  SDCachedURLResponse.m
+//  SDURLCache
+//
+//  Created by Olivier Poitrey on 12/05/12.
+//  Copyright (c) 2012 Dailymotion. All rights reserved.
+//
+
+#import "SDCachedURLResponse.h"
+
+@implementation SDCachedURLResponse
+
+@synthesize response;
+
++ (id)cachedURLResponseWithNSCachedURLResponse:(NSCachedURLResponse *)response
+{
+    SDCachedURLResponse *wrappedResponse = [[SDCachedURLResponse alloc] init];
+    wrappedResponse.response = response;
+    return [wrappedResponse autorelease];
+}
+
+#pragma mark NSCopying Methods
+
+- (id)copyWithZone:(NSZone *)zone
+{
+    SDCachedURLResponse *newResponse = [[[self class] allocWithZone:zone] init];
+
+    if (newResponse)
+    {
+        newResponse.response = [[self.response copyWithZone:zone] autorelease];
+    }
+
+    return newResponse;
+}
+
+#pragma mark NSCoding Methods
+- (void)encodeWithCoder:(NSCoder *)coder
+{
+    // force write the data of underlying cached response
+    [coder encodeDataObject:self.response.data];
+    [coder encodeObject:self.response.response forKey:@"response"];
+    [coder encodeObject:self.response.userInfo forKey:@"userInfo"];
+    [coder encodeInt:self.response.storagePolicy forKey:@"storagePolicy"];
+}
+
+- (id)initWithCoder:(NSCoder *)coder
+{
+    if ((self = [super init]))
+    {
+        self.response = [[[NSCachedURLResponse alloc] initWithResponse:[coder decodeObjectForKey:@"response"]
+                                                                  data:[coder decodeDataObject]
+                                                              userInfo:[coder decodeObjectForKey:@"userInfo"]
+                                                         storagePolicy:[coder decodeIntForKey:@"storagePolicy"]] autorelease];
+    }
+
+    return self;
+}
+
+- (void)dealloc
+{
+    [super dealloc];
+    [response release], response = nil;
+}
+
+@end

SDURLCache.h

@@ -13,7 +13,7 @@
     @private
     NSString *diskCachePath;
     NSMutableDictionary *diskCacheInfo;
-    BOOL diskCacheInfoDirty, ignoreMemoryOnlyStoragePolicy;
+    BOOL diskCacheInfoDirty, ignoreMemoryOnlyStoragePolicy, disabled;
     NSUInteger diskCacheUsage;
     NSTimeInterval minCacheInterval;
     NSOperationQueue *ioQueue;

SDURLCache.m

@@ -7,7 +7,18 @@
 //
 
 #import "SDURLCache.h"
+#import "SDCachedURLResponse.h"
 #import <CommonCrypto/CommonDigest.h>
+#import <UIKit/UIDevice.h>
+
+// The removal of the NSCachedURLResponse category means that NSKeyedArchiver
+// will throw an EXC_BAD_ACCESS when attempting to load NSCachedURLResponse
+// data.
+// This means that this change requires a cache refresh, and a new cache key
+// namespace that will prevent this from happening.
+// Old cache keys will eventually be evicted from the system as new keys are
+// populated.
+static NSString *const kSDURLCacheVersion = @"V2";
 
 static NSTimeInterval const kSDURLCacheInfoDefaultMinCacheInterval = 5 * 60; // 5 minute
 static NSString *const kSDURLCacheInfoFileName = @"cacheInfo.plist";
@@ -30,31 +41,6 @@
     return [dateFormatter autorelease];
 }
 
-@implementation NSCachedURLResponse(NSCoder)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wobjc-protocol-method-implementation"
-
-- (void)encodeWithCoder:(NSCoder *)coder
-{
-    [coder encodeDataObject:self.data];
-    [coder encodeObject:self.response forKey:@"response"];
-    [coder encodeObject:self.userInfo forKey:@"userInfo"];
-    [coder encodeInt:self.storagePolicy forKey:@"storagePolicy"];
-}
-
-- (id)initWithCoder:(NSCoder *)coder
-{
-    return [self initWithResponse:[coder decodeObjectForKey:@"response"]
-                             data:[coder decodeDataObject]
-                         userInfo:[coder decodeObjectForKey:@"userInfo"]
-                    storagePolicy:[coder decodeIntForKey:@"storagePolicy"]];
-}
-
-#pragma clang diagnostic pop
-
-@end
-
-
 @interface SDURLCache ()
 @property (nonatomic, retain) NSString *diskCachePath;
 @property (nonatomic, readonly) NSMutableDictionary *diskCacheInfo;
@@ -87,8 +73,8 @@ + (NSString *)cacheKeyForURL:(NSURL *)url
     const char *str = [url.absoluteString UTF8String];
     unsigned char r[CC_MD5_DIGEST_LENGTH];
     CC_MD5(str, strlen(str), r);
-    return [NSString stringWithFormat:@"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
-            r[0], r[1], r[2], r[3], r[4], r[5], r[6], r[7], r[8], r[9], r[10], r[11], r[12], r[13], r[14], r[15]];
+    return [NSString stringWithFormat:@"%@_%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
+            kSDURLCacheVersion, r[0], r[1], r[2], r[3], r[4], r[5], r[6], r[7], r[8], r[9], r[10], r[11], r[12], r[13], r[14], r[15]];
 }
 
 /*
@@ -368,7 +354,8 @@ - (void)balanceDiskUsage
 - (void)storeToDisk:(NSDictionary *)context
 {
     NSURLRequest *request = [context objectForKey:@"request"];
-    NSCachedURLResponse *cachedResponse = [context objectForKey:@"cachedResponse"];
+    // use wrapper to ensure we save appropriate fields
+    SDCachedURLResponse *cachedResponse = [SDCachedURLResponse cachedURLResponseWithNSCachedURLResponse:[context objectForKey:@"cachedResponse"]];
 
     NSString *cacheKey = [SDURLCache cacheKeyForURL:request.URL];
     NSString *cacheFilePath = [diskCachePath stringByAppendingPathComponent:cacheKey];
@@ -436,7 +423,12 @@ + (NSString *)defaultCachePath
 
 - (id)initWithMemoryCapacity:(NSUInteger)memoryCapacity diskCapacity:(NSUInteger)diskCapacity diskPath:(NSString *)path
 {
-    if ((self = [super initWithMemoryCapacity:memoryCapacity diskCapacity:diskCapacity diskPath:path]))
+    // iOS 5 implements disk caching. SDURLCache then disables itself at runtime if the current device OS
+    // version is 5 or greater
+    NSArray *version = [[UIDevice currentDevice].systemVersion componentsSeparatedByString:@"."];
+    disabled = [[version objectAtIndex:0] intValue] >= 5;
+
+    if ((self = [super initWithMemoryCapacity:memoryCapacity diskCapacity:diskCapacity diskPath:path]) && !disabled)
     {
         self.minCacheInterval = kSDURLCacheInfoDefaultMinCacheInterval;
         self.diskCachePath = path;
@@ -455,6 +447,12 @@ - (id)initWithMemoryCapacity:(NSUInteger)memoryCapacity diskCapacity:(NSUInteger
 
 - (void)storeCachedResponse:(NSCachedURLResponse *)cachedResponse forRequest:(NSURLRequest *)request
 {
+    if (disabled)
+    {
+        [super storeCachedResponse:cachedResponse forRequest:request];
+        return;
+    }
+
     request = [SDURLCache canonicalRequestForRequest:request];
 
     if (request.cachePolicy == NSURLRequestReloadIgnoringLocalCacheData
@@ -500,6 +498,8 @@ - (void)storeCachedResponse:(NSCachedURLResponse *)cachedResponse forRequest:(NS
 
 - (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request
 {
+    if (disabled) return [super cachedResponseForRequest:request];
+
     request = [SDURLCache canonicalRequestForRequest:request];
 
     NSCachedURLResponse *memoryResponse = [super cachedResponseForRequest:request];
@@ -517,7 +517,10 @@ - (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request
         NSMutableDictionary *accesses = [self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey];
         if ([accesses objectForKey:cacheKey]) // OPTI: Check for cache-hit in a in-memory dictionary before hitting the file system
         {
-            NSCachedURLResponse *diskResponse = [NSKeyedUnarchiver unarchiveObjectWithFile:[diskCachePath stringByAppendingPathComponent:cacheKey]];
+            // load wrapper
+            SDCachedURLResponse *diskResponseWrapper = [NSKeyedUnarchiver unarchiveObjectWithFile:[diskCachePath stringByAppendingPathComponent:cacheKey]];
+            NSCachedURLResponse *diskResponse = diskResponseWrapper.response;
+
             if (diskResponse)
             {
                 // OPTI: Log the entry last access time for LRU cache eviction algorithm but don't save the dictionary
@@ -547,6 +550,8 @@ - (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request
 
 - (NSUInteger)currentDiskUsage
 {
+    if (disabled) return [super currentDiskUsage];
+
     if (!diskCacheInfo)
     {
         [self diskCacheInfo];
@@ -556,6 +561,12 @@ - (NSUInteger)currentDiskUsage
 
 - (void)removeCachedResponseForRequest:(NSURLRequest *)request
 {
+    if (disabled)
+    {
+        [super removeCachedResponseForRequest:request];
+        return;
+    }
+
     request = [SDURLCache canonicalRequestForRequest:request];
 
     [super removeCachedResponseForRequest:request];
@@ -567,6 +578,7 @@ - (void)removeAllCachedResponses
 {
     [super removeAllCachedResponses];
 
+    if (disabled) return;
     NSFileManager *fileManager = [[NSFileManager alloc] init];
     [fileManager removeItemAtPath:diskCachePath error:NULL];
     [fileManager release];
@@ -586,7 +598,9 @@ - (BOOL)isCached:(NSURL *)url
     {
         return YES;
     }
-    
+
+    if (disabled) return NO;
+
     NSString *cacheKey = [SDURLCache cacheKeyForURL:url];
     NSString *cacheFile = [diskCachePath stringByAppendingPathComponent:cacheKey];
     NSFileManager *manager = [[NSFileManager alloc] init];
@@ -605,6 +619,12 @@ - (BOOL)isCached:(NSURL *)url
 
 - (void)dealloc
 {
+    if (disabled)
+    {
+        [super dealloc];
+        return;
+    }
+
     [periodicMaintenanceTimer invalidate];
     [periodicMaintenanceTimer release], periodicMaintenanceTimer = nil;
     [periodicMaintenanceOperation release], periodicMaintenanceOperation = nil;

SDURLCache.xcodeproj/project.pbxproj

@@ -7,6 +7,8 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		5318A9AB155DD7B500AB6767 /* SDCachedURLResponse.h in Headers */ = {isa = PBXBuildFile; fileRef = 5318A9A9155DD7B500AB6767 /* SDCachedURLResponse.h */; };
+		5318A9AC155DD7B500AB6767 /* SDCachedURLResponse.m in Sources */ = {isa = PBXBuildFile; fileRef = 5318A9AA155DD7B500AB6767 /* SDCachedURLResponse.m */; };
 		53F557F4114EA63600A3DA4B /* SDURLCache.h in Headers */ = {isa = PBXBuildFile; fileRef = 53F557F2114EA63600A3DA4B /* SDURLCache.h */; };
 		53F557F5114EA63600A3DA4B /* SDURLCache.m in Sources */ = {isa = PBXBuildFile; fileRef = 53F557F3114EA63600A3DA4B /* SDURLCache.m */; };
 		53F5592C114F1ED800A3DA4B /* SDURLCacheTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 53F5592B114F1ED800A3DA4B /* SDURLCacheTests.m */; };
@@ -25,6 +27,8 @@
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
+		5318A9A9155DD7B500AB6767 /* SDCachedURLResponse.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = SDCachedURLResponse.h; sourceTree = "<group>"; };
+		5318A9AA155DD7B500AB6767 /* SDCachedURLResponse.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = SDCachedURLResponse.m; sourceTree = "<group>"; };
 		53F557F2114EA63600A3DA4B /* SDURLCache.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = SDURLCache.h; sourceTree = "<group>"; };
 		53F557F3114EA63600A3DA4B /* SDURLCache.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = SDURLCache.m; sourceTree = "<group>"; };
 		53F5591C114F1D5E00A3DA4B /* SDURLCacheTestBundle.octest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = SDURLCacheTestBundle.octest; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -86,6 +90,8 @@
 			children = (
 				53F557F2114EA63600A3DA4B /* SDURLCache.h */,
 				53F557F3114EA63600A3DA4B /* SDURLCache.m */,
+				5318A9A9155DD7B500AB6767 /* SDCachedURLResponse.h */,
+				5318A9AA155DD7B500AB6767 /* SDCachedURLResponse.m */,
 			);
 			name = Classes;
 			sourceTree = "<group>";
@@ -116,6 +122,7 @@
 			files = (
 				AA747D9F0F9514B9006C5449 /* SDURLCache_Prefix.pch in Headers */,
 				53F557F4114EA63600A3DA4B /* SDURLCache.h in Headers */,
+				5318A9AB155DD7B500AB6767 /* SDCachedURLResponse.h in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -227,6 +234,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				53F557F5114EA63600A3DA4B /* SDURLCache.m in Sources */,
+				5318A9AC155DD7B500AB6767 /* SDCachedURLResponse.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};