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这是我的应用程序的布局。我在标签栏控制器中有一个 UICollectionView。我在服务器上有两个不同的 XML 文件。根据订阅购买，将解析两个 xml 中的一个，并将每个项目添加到一个数组中，然后 UICollectionView 会显示该数组。我使用 MKiCloudSync 跨 iCloud 存储 NSUserDefault 值作为确定订阅是否仍然有效的方法，因此用户可以在多个设备上访问该应用程序。

我在 AppDelegate 实现文件中调用[MKiCloudSync start];了 didFinishLaunchingWithOptions。

在 UICollectionViewController 文件中，布局本质上是这样的：

viewDidLoad 为 MKiCloudSync 更改添加侦听器。如果进行了更改，它将运行代码以更新 UI。viewWillAppear 检查 NSUserDefaults 以查看它是否应该加载付费或免费 XML，并据此进行解析。如果用户没有订阅，右栏按钮项目允许他们购买它，这会调用代码这样做。代码成功后，它会运行解析付费 xml 的代码 refreshpaid。

这是理论上的设置。我从 Ad Hoc build 在我的设备上运行该应用程序，并在沙盒环境中购买了订阅。UI 已按原样更新，以显示付费 XML 中可用的其他内容。

然后我删除了应用程序，重新启动了设备，并重新安装了临时构建以确保 iCloud 同步正常工作。当应用程序启动时，它为每个项目显示 11 个单元格（假设以某种方式刷新的代码以某种方式被调用了 11 次）。如果我导航到另一个选项卡并返回，或者单击一个单元格并弹回，它会自行更正并仅在 XML 中显示每个项目 1 个单元格。

现在，这是我的 UICollectionView.m 文件中的完整代码：

    - (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];       
                }

            }];

        }
    }];

}
4

1 回答 1

0

一种可能性：您应该始终确保显示的内容始终是您想要的。以这个为例：（来自我WFAsyncImageCell的 iOS，在 OS X 上基本相同。）

- (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];
            }
        });
    });
于 2013-06-29T14:11:27.350 回答