UICollectionView Cells Loading Same Items too many times - ios

Question

Here is the layout of my app. I have a UICollectionView in a Tab Bar Controller. I have two different XML files located on server. Depending on subscription purchases, one of two xmls will be parsed, and each item gets added to an array, which the UICollectionView in turn displays. I use MKiCloudSync to store the NSUserDefault values across iCloud as the method to determine if a subscription is still valid or not, so the user can access the app on multiple devices.
I call [MKiCloudSync start]; on didFinishLaunchingWithOptions in the AppDelegate implementation file.
In the UICollectionViewController file, the layout is essentially this:
viewDidLoad adds listener for MKiCloudSync changes. If change is made, it runs the code to update the UI. viewWillAppear checks the NSUserDefaults to see if it should load paid or free XML, and parses based off of that. If user does not have subscription, the right bar button item allows them to purchase it, which calls the code to do so. Upon successful code, it runs the code refreshpaid which parses the paid xml.
That is the setup in theory. I ran the app on my device from Ad Hoc build, and purchased the subscription in sandbox environment. The UI Updated as it should to show the additional content available in the Paid XML.
I then deleted the app, restarted the device, and reinstalled the ad hoc build to ensure the iCloud sync was working. When the app started, it showed 11 cells for every single item (assuming somehow code to refresh got called 11 times somehow). If I navigate to another tab and come back, or click on a cell and pop back, it corrects itself and just shows 1 cell per item in the XML.
Now, here is the full code from my UICollectionView.m file:
- (void)viewDidLoad {
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver: self selector: #selector(updatetheui) name: NSUserDefaultsDidChangeNotification object: nil];
UINib *cellNib = [UINib nibWithNibName:#"NibCell" bundle:nil];
[self.collectionView registerNib:cellNib forCellWithReuseIdentifier:#"cvCell"];
self.collectionView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"shelves.png"]];
}
-(void)updatetheui {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *status = [defaults objectForKey:#"Pay?"];
NSString *expirationdate = [defaults objectForKey:#"expiration"];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"MM/dd/yyyy"];
NSDate *date = [dateFormat dateFromString:expirationdate];
NSLog(#"Date: %#", [dateFormat stringFromDate:date]);
if ([status isEqualToString:#"PaidUp"]|([date timeIntervalSinceNow] > 0.0)) {
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Status" style:UIBarButtonItemStyleBordered target:self action:#selector(statusofsubscription)];
self.navigationItem.leftBarButtonItem = nil;
NSLog(#"UPDATEUI PAY");
[_allEntries removeAllObjects];
[self.collectionView reloadData];
[self refreshpaid];
} else {
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Subscribe" style:UIBarButtonItemStyleBordered target:self action:#selector(buyButtonTapped:)];
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Restore" style:UIBarButtonItemStyleBordered target:self action:#selector(timetorestore)];
[_allEntries removeAllObjects];
[self.collectionView reloadData];
[self refreshfree];
NSLog(#"UPDATEUI FREE");
}
}
- (void)viewWillAppear:(BOOL)animated {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *status = [defaults objectForKey:#"Pay?"];
NSString *expirationdate = [defaults objectForKey:#"expiration"];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"MM/dd/yyyy"];
NSDate *date = [dateFormat dateFromString:expirationdate];
NSLog(#"Date: %#", [dateFormat stringFromDate:date]);
if ([status isEqualToString:#"PaidUp"]|([date timeIntervalSinceNow] > 0.0)) {
[self refreshpaid];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Status" style:UIBarButtonItemStyleBordered target:self action:#selector(statusofsubscription)];
self.navigationItem.leftBarButtonItem = nil;
NSLog(#"WILLAPPEARPAID");
}
else {
[self refreshfree];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Subscribe" style:UIBarButtonItemStyleBordered target:self action:#selector(buyButtonTapped:)];
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Restore" style:UIBarButtonItemStyleBordered target:self action:#selector(timetorestore)];
}
//[self.tableView deselectRowAtIndexPath:self.tableView.indexPathForSelectedRow animated:YES];
}
- (void)viewWillDisappear:(BOOL)animated {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
-(void)timetorestore {
[MKiCloudSync start];
UIAlertView *syncing = [[UIAlertView alloc]initWithTitle:#"Syncing" message:#"Now attempting to restore your subscription from iCloud. If unsuccessful, your subscription may have expired, or you may need to try again in a stronger network." delegate:self cancelButtonTitle:#"Okay" otherButtonTitles: nil];
[syncing show];
[syncing release];
}
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
NSLog(#"1");
}
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return [_allEntries count];
NSLog(#"2");
}
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
[UIView animateWithDuration:5.0
delay:0
options:(UIViewAnimationOptionAllowUserInteraction)
animations:^{
NSLog(#"animation start");
[cell setBackgroundColor:[UIColor colorWithRed: 180.0/255.0 green: 238.0/255.0 blue:180.0/255.0 alpha: 1.0]];
}
completion:^(BOOL finished){
NSLog(#"animation end");
[cell setBackgroundColor:[UIColor whiteColor]];
}
];
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 30200
if( UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad )
{
if (_webViewController2 == nil) {
self.webViewController2 = [[[WebViewController2 alloc] initWithNibName:#"WebViewController2" bundle:[NSBundle mainBundle]] autorelease];
}
RSSEntry *entry = [_allEntries objectAtIndex:indexPath.row];
_webViewController2.entry = entry;
[self.navigationController pushViewController:_webViewController2 animated:YES];
}
else {
if (_webViewController == nil) {
self.webViewController = [[[WebViewController alloc] initWithNibName:#"WebViewController" bundle:[NSBundle mainBundle]] autorelease];
}
RSSEntry *entry = [_allEntries objectAtIndex:indexPath.row];
_webViewController.entry = entry;
[self.navigationController pushViewController:_webViewController animated:YES];
}
#endif
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
RSSEntry *entry = [_allEntries objectAtIndex:indexPath.row];
static NSString *cellIdentifier = #"cvCell";
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];
UIImageView *titleLabel = (UIImageView *)[cell viewWithTag:100];
UILabel *titleLabel2 = (UILabel *)[cell viewWithTag:200];
NSString *thearticleImage = entry.articleImage;
[titleLabel setImageWithURL:[NSURL URLWithString:entry.articleImage] placeholderImage:[UIImage imageNamed:#"icon#2x.png"]];
// [titleLabel2 setText:entry.articleTitle];
return cell;
}
- (void)parseRss:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {
NSArray *channels = [rootElement elementsForName:#"channel"];
for (GDataXMLElement *channel in channels) {
NSString *blogTitle = [channel valueForChild:#"title"];
NSArray *items = [channel elementsForName:#"item"];
for (GDataXMLElement *item in items) {
NSString *issueTitle = [item valueForChild:#"title"];
NSString *issueURL = [item valueForChild:#"link"];
NSString *articleDateString = [item valueForChild:#"pubDate"];
NSDate *articleDate = [NSDate dateFromInternetDateTimeString:articleDateString formatHint:DateFormatHintRFC822];
NSString *issueCoverArt = [item valueForChild:#"guid"];
NSLog(#"Title%#", issueTitle);
NSLog(#"Link%#", issueURL);
NSLog(#"Date%#", articleDateString);
NSLog(#"CoverArt%#", issueCoverArt);
RSSEntry *entry = [[[RSSEntry alloc] initWithBlogTitle:blogTitle
articleTitle:issueTitle
articleUrl:issueURL
articleDate:articleDate
articleImage:issueCoverArt] autorelease];
[entries addObject:entry];
}
}
}
- (void)parseFeed:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {
if ([rootElement.name compare:#"rss"] == NSOrderedSame) {
[self parseRss:rootElement entries:entries];
} else if ([rootElement.name compare:#"feed"] == NSOrderedSame) {
[self parseAtom:rootElement entries:entries];
} else {
NSLog(#"Unsupported root element: %#", rootElement.name);
}
}
- (void)requestFinished:(ASIHTTPRequest *)request {
[_queue addOperationWithBlock:^{
NSError *error;
GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithData:[request responseData]
options:0 error:&error];
if (doc == nil) {
NSLog(#"Failed to parse %#", request.url);
} else {
NSMutableArray *entries = [NSMutableArray array];
[self parseFeed:doc.rootElement entries:entries];
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
for (RSSEntry *entry in entries) {
int insertIdx = [_allEntries indexForInsertingObject:entry sortedUsingBlock:^(id a, id b) {
RSSEntry *entry1 = (RSSEntry *) a;
RSSEntry *entry2 = (RSSEntry *) b;
return [entry1.articleDate compare:entry2.articleDate];
}];
[_allEntries insertObject:entry atIndex:insertIdx];
[self.collectionView reloadData];
}
}];
}
}];
}

Answer 1

One possibility: you should always make sure that what get displayed is always what you intended. Take this as an example: (from my WFAsyncImageCell for iOS, it is largely the same principle on OS X.)
- (void)loadImage
{
if ([self.lastLoadedURL isEqual:self.imageURL])
{
return; // The current image URL is being reloaded. Ignore.
}
self.imageView.image = nil;
NSURL *loadURL = self.imageURL;
dispatch_group_async(WFBackgroundTasks,
dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,
0),
^
{
// Get the image data. Possible check cached data
NSData *imageData = [NSData dataWithContentsOfURL:loadURL];
UIImage *image = [[UIImage alloc] initWithData:imageData];
if (!image)
{
// Oops, image file downloaded is bad.
image = [UIImage imageNamed:#"defaultFallback"];
}
else
{
// Cache it. Not gonna implement here in the demo.
}
dispatch_async(dispatch_get_main_queue(),
^
{
if ([loadURL isEqual:self.imageURL])
{
self.imageView.image = image;
}
else
{
// Oops, reload.
[self loadImage];
}
});
});