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我正在UILabel从 Rotten Tomatoes API 获取我的值，并且我希望我的自定义单元格中的文本在已经获取值时更新。我尝试通过重新加载我的来做到这一点，UITableView但它继续循环。

这是我的代码：

if (ratingTomatoLabel.text == nil)
    {
        NSLog(@"   Nil");

        NSString *stringWithNoSpaces = [movieTitle.text stringByReplacingOccurrencesOfString:@" " withString:@"%20"];
        NSString *rottenTomatoRatingString = [NSString stringWithFormat:@"%@%@%@", @"http://api.rottentomatoes.com/api/public/v1.0/movies.json?apikey=6844abgw34rfjukyyvzbzggz&q=", stringWithNoSpaces, @"&page_limit=1"];
        NSLog(@"   Rotten URL: %@", rottenTomatoRatingString);
        NSURL *rottenUrl = [[NSURL alloc] initWithString:rottenTomatoRatingString];
        NSURLRequest *rottenRequest = [[NSURLRequest alloc] initWithURL:rottenUrl];

        AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:rottenRequest success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
            NSLog(@"      3");
            self.testDict = [JSON objectForKey:@"movies"];
        } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
            NSLog(@"Request Failed with Error: %@, %@", error, error.userInfo);
        }];

        [operation start];

        NSLog(@"   %@", ratingTomatoLabel.text);
        ratingTomatoLabel.text = @"...";
    }
    else if ([ratingTomatoLabel.text isEqualToString:@""])
    {
        NSLog(@"   isEqualToString");
        // Do nothing
    }
    else
    {
        NSLog(@"   else");
    }

    return tableCell;

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    NSLog(@"      fetched!");

    if ([ratingTomatoLabel.text isEqualToString:@"..."])
    {
        NSLog(@"      2nd nil");
        NSDictionary *dict = [self.testDict valueForKey:@"ratings"];
        self.criticsScoreString = [NSString stringWithFormat:@"%@", [dict valueForKey:@"critics_score"]];
        self.criticsScoreString = [self.criticsScoreString stringByReplacingOccurrencesOfString:@" " withString:@""];
        self.criticsScoreString = [self.criticsScoreString stringByReplacingOccurrencesOfString:@"(" withString:@""];
        self.criticsScoreString = [self.criticsScoreString stringByReplacingOccurrencesOfString:@")" withString:@""];
        self.criticsScoreString = [NSString stringWithFormat:@"%@%@", self.criticsScoreString, @"%"];

        ratingTomatoLabel.text = self.criticsScoreString;
        NSLog(@"      %@", ratingTomatoLabel.text);
    }
    else
    {
        NSLog(@"      2nd not nil");
        NSLog(@"      %@", ratingTomatoLabel.text);
        // Do nothing
    }
}

如果我[self.myTableView reloadData];在文本中设置值后添加代码，它会循环。最好的方法是什么？谢谢！

更新：包括更新的代码和另一种方法。另外，我的 ratingTomatoLabel 在不显示时总是为零。

4

2 回答 2

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杰特里克斯

由于 AFNetworking 调用异步发生，请考虑使用某种通知来告诉主线程 (UI) 工作何时完成或发生错误。

坦率

于 2013-02-05T09:29:52.003 回答
0

您应该使用KVO（键值观察）来检测字典或数组何时发生更改 - 在这种情况下，它似乎是self.testDict.

当您收到此通知时，请使用 UITableView 的-visibleCells方法仅更新可见单元格 - 其他单元格在使用-tableView:cellForRowAtIndexPath:.

KVO 需要什么：在视图加载/更改时注册/取消注册并设置您希望观察的变量...

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if([keyPath isEqual:@"testDict"])
    {
        NSLog(@"KVO change: %@", change);
        NSArray *visibleCells = [self.myTableView visibleCells];
        for(UITableViewCell *cell in visibleCells)
        {
            if(/*cell matches the one I'm targeting OR just update regardless*/)
                // assign value to UILabel
        }
    }
}

// Call this from -viewDidLoad
- (void)registerAsObserver
{
    [self addObserver:self forKeyPath:@"testDict" options:NSKeyValueObservingOptionNew context:NULL];
}

// Call this from -viewWillDisappear and -viewDidUnload (may not be necessary for -viewDidUnload if already implemented in -viewWillDisappear)
- (void)unregisterAsObserver
{
    [self removeObserver:self forKeyPath:@"testDict"];
}

最后，要更新已更改的单元格，请调用该-reloadRowsAtIndexPaths:withRowAnimation:方法让底层系统刷新该单元格。

于 2013-02-05T09:41:41.993 回答