我有一个带有两个uilabels的自定义表视图单元格，所有内容都正常启动但当我滚动到表格的另一部分并返回时，标签在任何地方都找不到。但是如果我选择它们，它们会再次显示，直到它们为止取消选择
- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
id appDelegate = [[UIApplication sharedApplication] delegate];
_managedObjectContext = [appDelegate managedObjectContext];
NSError *error;
if (![[self fetchedResultsController] performFetch:&error]) {
NSLog(@"%@ %@", error, [error userInfo]);
abort();
}
_infoView.layer.cornerRadius = 5;
_infoView.layer.masksToBounds = YES;
_infoView.layer.shadowColor = [UIColor colorWithRed:205.0/255.0 green:205.0/255.0 blue:205.0/255.0 alpha:1.0].CGColor;
_infoView.layer.shadowOpacity = 0.8;
_infoView.layer.shadowRadius = 10.0;
_infoView.layer.shadowOffset = CGSizeMake(2.0, 2.0);
_addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(add:)];
self.navigationItem.rightBarButtonItem = _addButton;
_searchBar.backgroundColor = [UIColor clearColor];
_searchBar.clipsToBounds = YES;
_searchBar.tintColor = [UIColor colorWithRed:200.0/255.0 green:200.0/255.0 blue:200.0/255.0 alpha:1.0];
for (UIView *subview in _searchBar.subviews)
{
if ([subview isKindOfClass:NSClassFromString(@"UISearchBarBackground")])
{
[subview removeFromSuperview];
break;
}
}
_exercisesNumberLabel.text = [NSString stringWithFormat:@"%lu Exercises", (unsigned long)[_fetchedResultsController.fetchedObjects count]];
[_exercisesNumberLabel sizeToFit];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[self.tableView setContentOffset:CGPointMake(0, _headerView.bounds.size.height)];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)add:(id)sender
{
}
#pragma mark - UITableViewDataSource
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return [[_fetchedResultsController sections] count];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
return [[[_fetchedResultsController sections] objectAtIndex:section] name];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
id <NSFetchedResultsSectionInfo> sectionInfo = [[_fetchedResultsController sections] objectAtIndex:section];
return [sectionInfo numberOfObjects];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *cellIdentifier = nil;
cellIdentifier = @"exerciseCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (!cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
[self stampCell:cell atIndexPath:indexPath];
}
[self configureCell:cell atIndexPath:indexPath];
return cell;
}
- (void)stampCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
UILabel *textLabel, *detailTextLabel;
UIButton *playButton;
//UIWebView *miniYouTubeView;
textLabel = [[UILabel alloc] initWithFrame:CGRectMake(70, 2, 170, 22)];
textLabel.tag = kExerciseCellTextLabel;
textLabel.font = [UIFont systemFontOfSize:17.0];
textLabel.textAlignment = NSTextAlignmentLeft;
textLabel.textColor = [UIColor blackColor];
[[cell contentView] addSubview:textLabel];
detailTextLabel = [[UILabel alloc] initWithFrame:CGRectMake(70, 24, 170, 18)];
detailTextLabel.tag = kExerciseCellDetailTextLabel;
detailTextLabel.font = [UIFont systemFontOfSize:14.0];
detailTextLabel.textAlignment = NSTextAlignmentLeft;
detailTextLabel.textColor = [UIColor colorWithRed:128.0/255.0 green:128.0/255.0 blue:128.0/255.0 alpha:1.0];
detailTextLabel.autoresizingMask = UIViewAutoresizingFlexibleRightMargin;
[[cell contentView] addSubview:detailTextLabel];
playButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 64, 44)];
playButton.backgroundColor = [UIColor lightGrayColor];
[playButton setImage:[UIImage imageNamed:@"121-landscape.png"] forState:UIControlStateNormal];
[[cell contentView] addSubview:playButton];
/*miniYouTubeView = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0, 60, 44)];
miniYouTubeView.tag = kExerciseCellMiniYouTubeView;
miniYouTubeView.autoresizingMask = UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleHeight;
[[cell contentView] addSubview:miniYouTubeView];*/
}
#pragma mark - UITableViewDelegate
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 44;
}
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
if ([[[_fetchedResultsController objectAtIndexPath:indexPath] isDefault] boolValue]) {
return NO;
}
return YES;
}
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleInsert) {
}
else if (editingStyle == UITableViewCellEditingStyleDelete) {
Exercise *exercise = [_fetchedResultsController objectAtIndexPath:indexPath];
[_managedObjectContext deleteObject:exercise];
NSError *error;
if (![_managedObjectContext save:&error]) {
NSLog(@"%@ %@", error, [error userInfo]);
abort();
}
}
}
#pragma mark - NSFetchedResultsControllerDelegate
- (NSFetchedResultsController *)fetchedResultsController
{
if (_fetchedResultsController) {
return _fetchedResultsController;
}
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:kExercise inManagedObjectContext:_managedObjectContext];
[request setEntity:entity];
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:kExerciseName ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
[request setSortDescriptors:sortDescriptors];
NSFetchedResultsController *fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:_managedObjectContext sectionNameKeyPath:kExerciseFirstLetter cacheName:@"ExerciseList"];
[self setFetchedResultsController:fetchedResultsController];
[_fetchedResultsController setDelegate:self];
return _fetchedResultsController;
}
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
[self.tableView beginUpdates];
}
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
switch(type) {
case NSFetchedResultsChangeInsert:
[self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath
{
UITableView *tableView = self.tableView;
switch(type) {
case NSFetchedResultsChangeInsert:
[tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
[self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
[self.tableView endUpdates];
}
- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
Exercise *exercise = [_fetchedResultsController objectAtIndexPath:indexPath];
UILabel *textLabel = (UILabel *)[[cell contentView] viewWithTag:kExerciseCellTextLabel];
UILabel *detailTextLabel = (UILabel *)[[cell contentView] viewWithTag:kExerciseCellDetailTextLabel];
//UIWebView *miniYouTubeView = (UIWebView *)[[cell contentView] viewWithTag:kExerciseCellMiniYouTubeView];
textLabel.text = [exercise valueForKey:kExerciseName];
detailTextLabel.text = [NSString stringWithFormat:@"%@ - %@", [[exercise valueForKey:kExerciseEType] valueForKey:kExerciseTypeName], [[exercise valueForKey:kGear] valueForKey:kGearName]];
//[textLabel sizeToFit];
//[detailTextLabel sizeToFit];
/*[miniYouTubeView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:[exercise valueForKey:kExerciseUrlAddress]]]];
[miniYouTubeView setScalesPageToFit:YES];
[miniYouTubeView setAutoresizesSubviews:YES];*/
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
答案 0 :(得分：1)
在滚动表格时会重复使用单元格。但是，您的代码编写方式使您每次重复使用单元格时都会添加越来越多的子视图。
如果stampCell为cell，则只能致电nil。
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
NSString *cellIdentifier = @"exerciseCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (!cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
[self stampCell:cell atIndexPath:indexPath];
}
[self configureCell:cell atIndexPath:indexPath];
return cell;
}
更好的解决方案是将UITableViewCell子类化，并将所有逻辑放在单元格而不是视图控制器中。