Making the previous button take you to the previous story you read. Obviously.

media/iphone/Classes/NewsBlurAppDelegate.h

@@ -37,6 +37,7 @@
     NSInteger selectedIntelligence;
     NSMutableArray * recentlyReadStories;
     NSIndexPath * activeFeedIndexPath;
+    NSMutableArray * readStories;
 }
 
 @property (nonatomic, retain) IBOutlet UIWindow *window;
@@ -61,6 +62,7 @@
 @property (readwrite) NSInteger selectedIntelligence;
 @property (readwrite, retain) NSMutableArray * recentlyReadStories;
 @property (readwrite, retain) NSIndexPath * activeFeedIndexPath;
+@property (readwrite, retain) NSMutableArray * readStories;
 
 - (void)showLogin;
 - (void)loadFeedDetailView;
@@ -71,10 +73,15 @@
 - (void)setTitle:(NSString *)title;
 - (void)showOriginalStory:(NSURL *)url;
 - (void)closeOriginalStory;
+
 - (int)indexOfNextStory;
 - (int)indexOfPreviousStory;
 - (int)indexOfActiveStory;
 - (int)locationOfActiveStory;
+- (void)pushReadStory:(id)storyId;
+- (id)popReadStory;
+- (int)locationOfStoryId:(id)storyId;
+
 - (void)setStories:(NSArray *)activeFeedStoriesValue;
 - (void)addStories:(NSArray *)stories;
 - (int)unreadCount;

media/iphone/Classes/NewsBlurAppDelegate.m

@@ -36,6 +36,7 @@
 @synthesize activeOriginalStoryURL;
 @synthesize recentlyReadStories;
 @synthesize activeFeedIndexPath;
+@synthesize readStories;
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
     navigationController.viewControllers = [NSArray arrayWithObject:feedsViewController];
@@ -73,6 +74,7 @@
     [activeOriginalStoryURL release];
     [recentlyReadStories release];
     [activeFeedIndexPath release];
+    [readStories release];
     [super dealloc];
 }
 
@@ -194,6 +196,31 @@
     return -1;
 }
 
+- (void)pushReadStory:(id)storyId {
+    if ([self.readStories lastObject] != storyId) {
+        [self.readStories addObject:storyId];
+    }
+}
+
+- (id)popReadStory {
+    if (storyCount == 0) {
+        return nil;
+    } else {
+        [self.readStories removeLastObject];
+        id lastStory = [self.readStories lastObject];
+        return lastStory;
+    }
+}
+
+- (int)locationOfStoryId:(id)storyId {
+    for (int i=0; i < [activeFeedStoryLocations count]; i++) {
+        if ([activeFeedStoryLocationIds objectAtIndex:i] == storyId) {
+            return [[activeFeedStoryLocations objectAtIndex:i] intValue];
+        }
+    }
+    return -1;
+}
+
 - (int)unreadCount {
     int total = 0;
     total += [[self.activeFeed objectForKey:@"ps"] intValue];
@@ -225,10 +252,10 @@
 
 - (void)markActiveStoryRead {
     int activeLocation = [self locationOfActiveStory];
-    int activeIndex = [[activeFeedStoryLocations objectAtIndex:activeLocation] intValue];
     if (activeLocation == -1) {
         return;
     }
+    int activeIndex = [[activeFeedStoryLocations objectAtIndex:activeLocation] intValue];
     
     NSDictionary *story = [activeFeedStories objectAtIndex:activeIndex];
     [story setValue:[NSNumber numberWithInt:1] forKey:@"read_status"];

media/iphone/Classes/NewsBlurViewController.m

@@ -409,6 +409,7 @@ blue:((float)(rgbValue & 0xFF))/255.0 alpha:1.0]
 	
 	[appDelegate setActiveFeed:feed];
 	[appDelegate setActiveFeedIndexPath:indexPath];
+	appDelegate.readStories = [NSMutableArray array];
 	
 	[appDelegate loadFeedDetailView];
 }

media/iphone/Classes/StoryDetailViewController.m

@@ -43,7 +43,9 @@
 
 - (void)viewWillAppear:(BOOL)animated {
 //    NSLog(@"Stories; %@ -- %@ (%d)", self.activeStoryId,  [appDelegate.activeStory objectForKey:@"id"], self.activeStoryId ==  [appDelegate.activeStory objectForKey:@"id"]);
-    if (self.activeStoryId != [appDelegate.activeStory objectForKey:@"id"]) {
+    id storyId = [appDelegate.activeStory objectForKey:@"id"];
+    if (self.activeStoryId != storyId) {
+        [appDelegate pushReadStory:storyId];
         [self setActiveStory];
         [self showStory];
         [self markStoryAsRead];   
@@ -83,8 +85,10 @@
         [buttonNext setTitle:@"Next Unread"];
     }
     
-    int previousIndex = [appDelegate indexOfPreviousStory];
-    if (previousIndex == -1) {
+    int readStoryCount = [appDelegate.readStories count];
+    if (readStoryCount == 0 || 
+        (readStoryCount == 1 && 
+         [appDelegate.readStories lastObject] == [appDelegate.activeStory objectForKey:@"id"])) {
         [buttonPrevious setTitle:@"Done"];
     } else {
         [buttonPrevious setTitle:@"Previous"];
@@ -255,6 +259,7 @@
     } else {
         [appDelegate setActiveStory:[[appDelegate activeFeedStories] 
                                      objectAtIndex:nextIndex]];
+        [appDelegate pushReadStory:[appDelegate.activeStory objectForKey:@"id"]];
         [self setActiveStory];
         [self showStory];
         [self markStoryAsRead];
@@ -271,13 +276,17 @@
 }
 
 - (IBAction)doPreviousStory {
-    int previousIndex = [appDelegate indexOfPreviousStory];
-    if (previousIndex == -1) {
+    id previousStoryId = [appDelegate popReadStory];
+    if (!previousStoryId || previousStoryId == [appDelegate.activeStory objectForKey:@"id"]) {
         [appDelegate.navigationController 
          popToViewController:[appDelegate.navigationController.viewControllers 
                               objectAtIndex:0]  
          animated:YES];
     } else {
+        int previousIndex = [appDelegate locationOfStoryId:previousStoryId];
+        if (previousIndex == -1) {
+            return [self doPreviousStory];
+        }
         [appDelegate setActiveStory:[[appDelegate activeFeedStories] 
                                      objectAtIndex:previousIndex]];
         [self setActiveStory];