Cleanup and clarification

Correct selector

[NSDate stopMockingDate];

Update .podspec

PINRemoteImage.podspec

@@ -70,7 +70,7 @@ Pod::Spec.new do |s|
 
   s.subspec "PINCache" do |pc|
     pc.dependency 'PINRemoteImage/Core'
-    pc.dependency 'PINCache', '=3.0.1-beta.6'
+    pc.dependency 'PINCache', '=3.0.1-beta.7'
     pc.ios.deployment_target = ios_deployment
     pc.tvos.deployment_target = tvos_deployment
     pc.osx.deployment_target = osx_deployment

Source/Classes/PINRemoteImageManager.m

@@ -168,12 +168,12 @@ - (nonnull instancetype)initWithSessionConfiguration:(nullable NSURLSessionConfi
 {
     if (self = [super init]) {
         if (imageCache) {
-            self.isTtlCache = [imageCache respondsToSelector:@selector(setObjectforKey:withAgeLimit:)];
             self.cache = imageCache;
         } else {
             self.cache = [self defaultImageCache];
         }
-
+        self.isTtlCache = [self.cache respondsToSelector:@selector(setObjectOnDisk:forKey:withAgeLimit:)];
+
         _sessionConfiguration = [configuration copy];
         if (!_sessionConfiguration) {
             _sessionConfiguration = [NSURLSessionConfiguration ephemeralSessionConfiguration];
@@ -240,14 +240,13 @@ - (nonnull instancetype)initWithSessionConfiguration:(nullable NSURLSessionConfi
         [pinDefaults setInteger:kPINRemoteImageDiskCacheVersion forKey:kPINRemoteImageDiskCacheVersionKey];
     }
 
-    self.isTtlCache = YES;
     return [[PINCache alloc] initWithName:kPINRemoteImageDiskCacheName rootPath:cacheURLRoot serializer:^NSData * (id <NSCoding>  _Nonnull object, NSString * _Nonnull key) {
         id <NSCoding, NSObject> obj = (id <NSCoding, NSObject>)object;
         if ([key hasPrefix:PINRemoteImageCacheKeyResumePrefix]) {
             return [NSKeyedArchiver archivedDataWithRootObject:obj];
         }
         return (NSData *)object;
-    } deserializer:^id <NSCoding> _Nonnull(NSData *_Nonnull data, NSString *_Nonnull key) {
+    } deserializer:^id <NSCoding> _Nonnull(NSData * _Nonnull data, NSString * _Nonnull key) {
         if ([key hasPrefix:PINRemoteImageCacheKeyResumePrefix]) {
             return [NSKeyedUnarchiver unarchiveObjectWithData:data];
         }
@@ -832,6 +831,8 @@ - (void)downloadImageWithURL:(NSURL *)url
                             }
 
                             date = [sRFC7231PreferredDateFormatter dateFromString:expires];
+
+                            // Invalid dates (notably "0") or dates in the past must not be cached (RFC7231 5.3)
                             maxAge = @((NSInteger) MAX(([date timeIntervalSinceNow]), 0));
                         }
                     }
@@ -1423,6 +1424,7 @@ - (BOOL)materializeAndCacheObject:(id)object
             if (maxAge && _isTtlCache) {
                 [self.cache setObjectOnDisk:diskData forKey:key withAgeLimit:[maxAge integerValue]];
             } else {
+                // unset (nil) maxAge, or a cache that is not _isTtlCache behave as before (will use cache global ageLimit)
                 [self.cache setObjectOnDisk:diskData forKey:key];
             }
         }

Tests/PINRemoteImageTests.m

@@ -968,7 +968,6 @@ - (void)testMaxAge
 
     diskCachedObj = [cache objectFromDiskForKey:key];
     XCTAssert(diskCachedObj == nil, @"Image was not discarded from the disk cache");
-
     [NSDate stopMockingDate];
 
     // nonTransparentWebPURL includes the header "expires: <about 1 yr from now>"
@@ -987,6 +986,7 @@ - (void)testMaxAge
 
     diskCachedObj = [cache objectFromDiskForKey:key];
     XCTAssert(diskCachedObj == nil, @"Image #2 was not discarded from the disk cache");
+    [NSDate stopMockingDate];
 }
 
 - (void)testAuthentication