在UITableView單元中重疊圖像的問題

Question

我在coredata sqlite Painter和Picture中有2個表格。關係一對多。 在表「圖片」我有字符串屬性pictureName。我存儲在磁盤 此代碼，我添加imageViews細胞上的圖像（153）：

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    NSError *error = nil; 
    if (![[self fetchedResultsController] performFetch:&error]) { 
     NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
     abort(); 
    } 
    self.tableView.transform = CGAffineTransformMakeRotation(-M_PI/2); 
    self.tableView.showsHorizontalScrollIndicator = NO; 
    self.tableView.showsVerticalScrollIndicator = NO; 
    [self.tableView setFrame:CGRectMake(0, 156, 1024, 449)]; 
} 

- (void)viewDidUnload 
{ 
    [self setTableView:nil]; 
    [super viewDidUnload]; 
    // Release any retained subviews of the main view. 
    // e.g. self.myOutlet = nil; 
} 

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation 
{ 
    // Return YES for supported orientations 
    return YES; 
} 
#pragma mark - UITableView Delegate Methods 
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{ 
    return [[fetchedResultsController fetchedObjects] count]; 
} 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    Painter *painter = [[fetchedResultsController fetchedObjects] objectAtIndex:section]; 
    //NSLog(@"%i", [painter.pictures count]); 
    return [painter.pictures count]; 
    //return 152; 
} 
- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath { 
    Painter *painter = [[fetchedResultsController fetchedObjects] objectAtIndex:indexPath.section]; 
    Picture *picture = [[painter.pictures allObjects] objectAtIndex:indexPath.row]; 
    UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:[NSString stringWithFormat:@"%@s.jpg", picture.imgName]]]; 
    NSLog(@"add image %@s.jpg to sector:%i row:%i", picture.imgName, indexPath.section, indexPath.row); 
    imageView.transform = CGAffineTransformMakeRotation(M_PI/2); 
    [cell addSubview:imageView]; 
    [imageView release]; 
} 

- (UITableViewCell *)tableView:(UITableView *)tableViewCurrent cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *CellIdentifier = @"Cell"; 

    UITableViewCell *cell = [tableViewCurrent dequeueReusableCellWithIdentifier:CellIdentifier]; 
    if (cell == nil) { 
     cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; 
    } 

    // Configure the cell. 
    [self configureCell:cell atIndexPath:indexPath]; 
    return cell; 
} 
- (CGFloat)tableView:(UITableView *)aTableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { 
    return 300.0; 
} 

- (void)tableView:(UITableView *)aTableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
} 


#pragma mark - Fetched results controller 

- (NSFetchedResultsController *)fetchedResultsController 
{ 
    if (fetchedResultsController != nil) { 
     return fetchedResultsController; 
    } 

    // Create the fetch request for the entity. 
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; 
    // Edit the entity name as appropriate. 
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Painter" inManagedObjectContext:managedObjectContext]; 
    [fetchRequest setEntity:entity]; 

    // Set the batch size to a suitable number. 
    [fetchRequest setFetchBatchSize:20]; 

    // Edit the sort key as appropriate. 

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:NO]; 
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; 

    [fetchRequest setSortDescriptors:sortDescriptors]; 


    // Edit the section name key path and cache name if appropriate. 
    // nil for section name key path means "no sections". 
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:@"Main"]; 
    aFetchedResultsController.delegate = self; 
    self.fetchedResultsController = aFetchedResultsController; 

    [aFetchedResultsController release]; 
    [fetchRequest release]; 
    [sortDescriptor release]; 
    [sortDescriptors release]; 

    return fetchedResultsController; 
} 

` 我有問題：很多照片的每一個細胞 http://ge.tt/9QX5lc4?c （選擇視圖按鈕） 爲什麼呢？

Answer 1

細胞正在被重複使用。每次配置單元格時，都會將圖像視圖添加爲子視圖。隨着時間的推移，這些積累和提供你所看到的效果。您應該檢查一個圖像視圖是否已經存在，併爲其分配一個圖像或先清理該單元，然後用圖像進行設置。

Answer 2

下面的代碼是什麼原因造成了你的問題：重新使用它在後續調用

static NSString *CellIdentifier = @"Cell"; 

UITableViewCell *cell = [tableViewCurrent dequeueReusableCellWithIdentifier:CellIdentifier]; 
if (cell == nil) { 
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; 
} 
// Configure the cell. 
[self configureCell:cell atIndexPath:indexPath]; 
return cell; 

你基本上緩存電池它的創建，並在第一時間tableView:cellForRowAtIndexPath:如果不這樣做希望這被緩存，那麼你需要每次創建一個新的單元格。

UITableViewCell *cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; 
// Configure the cell. 
[self configureCell:cell atIndexPath:indexPath]; 
return cell; 

這應該解決您的問題。有更多精細的處理單元格的方法，例如直接緩存它並直接操作它的子視圖，而不是每次重新創建它。在繼續處理代碼時需要注意的事項。