ios - 自定义 UITableView 单元格中的 UILabel 未随核心数据更改更新

Question

我正在尝试构建一个游戏计分应用程序，该应用程序使用带有玩家照片、姓名、按钮等的自定义表格单元格......在点击我的保存方法的表格 View 的自定义单元格中直接有添加/减去按钮，并将其存储回该特定用户的核心数据中。

问题是屏幕上的分数没有更新和反射(reflect)变化。对 Core Data 的保存操作完成后，我将调用 [self.tableView reloadData];... 什么都不做。但是，如果我重新启动该应用程序，则会出现得分变化(对于我点击过的任何球员)。

也许我让这件事变得比它需要的更难，或者我只是没有捕获真正的问题。

想法/评论？提前致谢。:-)

抱歉，如果这有点矫枉过正，但这是我的大部分实现文件:

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self resetViews];
}

- (void)viewDidLoad {
    [super viewDidLoad];

    AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = [appDelegate managedObjectContext];
    [context setUndoManager:nil];
    _managedObjectContext = context;

    self.tableView.delegate = self;

    [self setNeedsStatusBarAppearanceUpdate];
}


-(void)resetViews {

    NSLog(@"\n\n\nresetViews()");

    [self setupFetchedResultsController];
    [self.tableView reloadData];
    [self.view setNeedsDisplay];
}

- (void)setupFetchedResultsController {

    NSString *entityName = @"Players";
    NSLog(@"Setting up a Fetched Results Controller for the Entity named %@", entityName);

    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:entityName];

    request.sortDescriptors = [NSArray arrayWithObject:
                               [NSSortDescriptor
                                sortDescriptorWithKey:@"playerName"
                                ascending:YES
                                selector:@selector(localizedCaseInsensitiveCompare:)]];

    self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
                                                                        managedObjectContext:self.managedObjectContext
                                                                          sectionNameKeyPath:nil
                                                                                   cacheName:nil];

    NSError *error;
    NSArray *results = [_managedObjectContext executeFetchRequest:request error:&error];
    _playerArray = [[NSMutableArray alloc]initWithArray:results];

    NSLog(@"_playerArray count: %i", [_playerArray count]);
    NSLog(@"\n");
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return _playerArray.count;
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *cellIdentifier = @"playerCell";
    ScoringCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];

    // Configure the cell...
    Players *player_info = [_playerArray objectAtIndex:indexPath.row];

    NSSet *score = player_info.scores;

    for (Scoring *perObj in score){
        cell.lblPlayerScore.text = [perObj.score stringValue];
        NSLog(@"\n\n\n score for %@: %@", player_info.playerName, perObj.score);
    }

    cell.lblPlayerName.text = player_info.playerName;
    cell.lblPlayerNickName.text = player_info.playerNickName;
    cell.btnIncreaseScore.tag = indexPath.row;
    cell.btnDecreaseScore.tag = indexPath.row;
    cell.imgPlayerPhoto.image = [UIImage imageNamed:@"tmp_playerImage"];

    return cell;
}


- (IBAction)increaseScore:(id)sender {

    NSLog(@"PageContentViewController: increaseScore()");
    UIButton* btn=(UIButton*)sender;
    int selectedPlayerInt = btn.tag;
    //NSLog(@"Selected row is: %d",btn.tag);

    Players *player_info = [_playerArray objectAtIndex:selectedPlayerInt];
    [self updateRowScore:player_info:@"add"];
}

- (IBAction)decreaseScore:(id)sender {

    NSLog(@"PageContentView: decreaseScore()");
    UIButton* btn=(UIButton*)sender;
    int selectedPlayerInt = btn.tag;
    //NSLog(@"Selected row is: %d",btn.tag);

    Players *player_info = [_playerArray objectAtIndex:selectedPlayerInt];
    [self updateRowScore:player_info:@"subtract"];
}

-(void)updateRowScore: (Players *)player_info :(NSString *)modifier {

    NSLog(@"\n\nupdateRowScore()");
    NSLog(@"Update score (%@) for: %@\n", modifier, player_info.playerName);

    NSArray *scoreDataArray;

    if ([self playerScoreCount:player_info] == 0) {

        // NEW score... we've never scored before.
        Scoring *scoring_data = [NSEntityDescription
                                 insertNewObjectForEntityForName:@"Scoring"
                                 inManagedObjectContext:_managedObjectContext];

        //Since this is the first score, always set it to 1
        scoring_data.score = [NSNumber numberWithInt:1];
        scoring_data.holeNumber = [NSNumber numberWithInt:_pageIndex];
        scoring_data.scoredBy = player_info;

    } else {

        //Update existing player score..
        NSError *error = nil;
        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

        NSEntityDescription *BEntity = [NSEntityDescription entityForName:@"Scoring" inManagedObjectContext:_managedObjectContext];
        [fetchRequest setEntity:BEntity];

        NSPredicate *predicate = [NSPredicate
                                  predicateWithFormat:@"(scoredBy = %@)", [player_info objectID]];
        [fetchRequest setPredicate:predicate];

        NSArray *results = [_managedObjectContext executeFetchRequest:fetchRequest error:&error];
        scoreDataArray = [[NSMutableArray alloc]initWithArray:results];

        Scoring *score_update = [scoreDataArray objectAtIndex:0];
        int currentScore = [score_update.score intValue];
        NSLog(@"current score: %d", currentScore);

        if ([modifier  isEqual: @"add"]) {
            currentScore++;
        } else {

            // Don't allow negative scores.
            if (currentScore >= 1) {
                currentScore--;
            } else {
                currentScore = 0;
            }
        }

        NSLog(@"NEW score: %d", currentScore);
        score_update.score = [NSNumber numberWithInt:currentScore];
    }


    // write to database
    [self.managedObjectContext save:nil];

    [self resetViews];
}

---

更新:感谢 bbarnhart 的提示...我之前已经通读了那篇文章，并将其用作我开始的基础。决定更进一步，使用更多 Ray Wenderlich 示例重构一大块代码。

我已经看到对正在记录的内容进行了一些改进，并通过 NSLog 进行了报告...但是 View 仍然没有改变。

操作是增加分数，然后我使用 [self configureCell:cell atIndexPath:path]; 重置单元格在那里...负责将文本发送到的方法显示...NSLog 正在显示 2014-12-04 22:40:40.199 appName[7153:150248] Tim 的分数:4 而显示仍然只显示 3。

我知道这是一些愚蠢的菜鸟举动......我只是在做一些我无法弄清楚的错误。这是修改后的代码片段。

- (NSFetchedResultsController *)fetchedResultsController {

    if (_fetchedResultsController != nil) {
        return _fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription
                                   entityForName:@"Players"
                                   inManagedObjectContext:_managedObjectContext];
    [fetchRequest setEntity:entity];

    NSSortDescriptor *sort = [[NSSortDescriptor alloc]
                              initWithKey:@"playerName" ascending:YES];

    [fetchRequest setSortDescriptors:[NSArray arrayWithObject:sort]];

    NSFetchedResultsController *theFetchedResultsController =
    [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                        managedObjectContext:_managedObjectContext
                                        sectionNameKeyPath:nil
                                        cacheName:@"Root"];

    self.fetchedResultsController = theFetchedResultsController;
    _fetchedResultsController.delegate = self;

    NSError *error;
    NSArray *results = [_managedObjectContext executeFetchRequest:fetchRequest error:&error];
    _playerArray = [[NSMutableArray alloc]initWithArray:results];
    NSLog(@"_playerArray count: %i", [_playerArray count]);

    return _fetchedResultsController;
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {       
    id  sectionInfo = [[_fetchedResultsController sections] objectAtIndex:section];
    return [sectionInfo numberOfObjects];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *cellIdentifier = @"playerCell";
    ScoringCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (!cell) {
        cell = [[ScoringCell alloc] initWithStyle:UITableViewCellStyleSubtitle 
                                   reuseIdentifier:cellIdentifier];
    }

    [self configureCell:cell atIndexPath:indexPath];
    return cell;
}

- (void)configureCell:(ScoringCell *)cell atIndexPath:(NSIndexPath *)indexPath {

    Players *player_info = [_fetchedResultsController objectAtIndexPath:indexPath];
    NSSet *scoreSet = player_info.scores;

    NSString *cell_score;   
    for (Scoring *scoreObj in scoreSet) {
        cell_score = [scoreObj.score stringValue];
    }

    NSLog(@"Score for %@: %@", player_info.playerName, cell_score);

    if (cell_score != nil) {
        cell.lblPlayerScore.text = cell_score;
    }

    cell.lblPlayerName.text = player_info.playerName;
    cell.lblPlayerNickName.text = player_info.playerNickName;
    cell.btnIncreaseScore.tag = indexPath.row;
    cell.btnDecreaseScore.tag = indexPath.row;
    cell.imgPlayerPhoto.image = [UIImage imageNamed:@"demo_playerb"];

    [self resetViews];
    NSLog(@"\n");
}

- (IBAction)increaseScore:(id)sender {

    NSLog(@"PageContentViewController: increaseScore()");
    UIButton *senderButton = (UIButton *)sender;
    int selectedPlayerInt = senderButton.tag;
    NSIndexPath *path = [NSIndexPath indexPathForRow:senderButton.tag inSection:0];

    Players *player_info = [_playerArray objectAtIndex:selectedPlayerInt];
    [self updateRowScore:player_info:@"add":selectedPlayerInt:path];
}

-(void)updateRowScore:(Players *)player_info :(NSString *)modifier :(int)selectedPlayerInt :(NSIndexPath *)path  {

    NSArray *scoreDataArray;
    if ([self playerScoreCount:player_info] == 0) {

        // NEW score... we've never scored before.
        Scoring *scoring_data = [NSEntityDescription
                                 insertNewObjectForEntityForName:@"Scoring"
                                 inManagedObjectContext:_managedObjectContext];

        //Since this is the first score, always set it to 1
        scoring_data.score = [NSNumber numberWithInt:1];
        scoring_data.holeNumber = [NSNumber numberWithInt:_pageIndex];
        scoring_data.scoredBy = player_info;

    } else {

        //Update existing player score..

        NSError *error = nil;
        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

        NSEntityDescription *BEntity = [NSEntityDescription entityForName:@"Scoring" 
                                  inManagedObjectContext:_managedObjectContext];
        [fetchRequest setEntity:BEntity];

        NSPredicate *predicate = [NSPredicate
                                  predicateWithFormat:@"(scoredBy = %@)", [player_info objectID]];
        [fetchRequest setPredicate:predicate];

        NSArray *results = [_managedObjectContext executeFetchRequest:fetchRequest error:&error];
        scoreDataArray = [[NSMutableArray alloc]initWithArray:results];

        Scoring *score_update = [scoreDataArray objectAtIndex:0];
        int currentScore = [score_update.score intValue];
        NSLog(@"current score: %d", currentScore);

        if ([modifier  isEqual: @"add"]) {

            currentScore++;
        } else {

            // Don't allow negative scores.
            if (currentScore >= 1) {
                currentScore--;
            } else {
                currentScore = 0;
            }
        }

        NSLog(@"NEW score: %d", currentScore);
        score_update.score = [NSNumber numberWithInt:currentScore];
    }


    // write to database
    [self.managedObjectContext save:nil];


    static NSString *cellIdentifier = @"playerCell";
    ScoringCell *cell = [_tableView dequeueReusableCellWithIdentifier:cellIdentifier];


    [self configureCell:cell atIndexPath:path]; 
    [self resetViews];  
}

------------

更新:自从我有机会重新访问以来已经有一段时间了，并且在启用您的提示后才注意到一个新问题。在列表中向下或向上滚动并超出正常边界时，表格 View 数据似乎会覆盖当前行上方或下方行的显示。奇怪...不确定这个动画 Gif 是否会出现在 Stack 中。这是一个例子:

Answer 1

您的 TableView 未动态更新的主要原因是 NSFetchedResultsController 在发生更改时使用委托(delegate)进行通知。您需要设置该委托(delegate)，self.fetchedResultsController.delegate = self，然后添加委托(delegate)方法。

这是一个link to an example用于使用 NSFetchedResultsController 管理 UITableView。

更新

实现这些 NSFetchResultsController 委托(delegate)方法以允许您的表动态更新。

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath: (NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id )sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type

通常，这些方法包含用于更新表格的样板代码，您也可以在上面的链接中找到这些代码。