ios - 更改单元格的背景颜色

Question

如果插入了新项目，是否可以更改表格单元格的背景颜色。我可以更改所有单元格的背景颜色，但我只能更改新添加的单元格之一来更改颜色。

有什么办法可以做到这一点吗？

- (void)insertNewObject:(OutgoingHolder*)expense {
    NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
    NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
    Outgoing *outgoing = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];

    // If appropriate, configure the new managed object.
    // Normally you should use accessor methods, but using KVC here avoids the need to add a custom class to the template.
    //[newManagedObject setValue:[NSDate date] forKey:@"timeStamp"];

    // Save the context.

    outgoing.costDescription = expense.costDescription;
    outgoing.amount = [NSNumber numberWithFloat:expense.amount];
    outgoing.date = expense.date;
    outgoing.category = expense.category;


    NSError *error = nil;
    if (![context save:&error]) {
        // Replace this implementation with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    //CHANGES HERE
    self.addedNewRow=0;
    [self.tableView reloadData];
}





#pragma mark - Table View

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return [[self.fetchedResultsController sections] count];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    id <NSFetchedResultsSectionInfo> sectionInfo = [self.fetchedResultsController sections][section];
    return [sectionInfo numberOfObjects];
}

-(NSString*) tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section{

    id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section];

    return[sectionInfo name];


}

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

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
    [self configureCell:cell atIndexPath:indexPath];

    if (_total > 0.0 ) {
        //UPDATE 1:
        NSLog(@"%@",[@"Total : " stringByAppendingString:[NSString stringWithFormat:@"%.2f", self.total]]);
        id <NSFetchedResultsSectionInfo> sectionInfo = [self.fetchedResultsController sections][indexPath.section];
        if ([sectionInfo numberOfObjects]-1  == indexPath.row  && self.addedNewRow!=-1) {
            cell.contentView.backgroundColor = [UIColor orangeColor];
            [cell.textLabel setBackgroundColor:[UIColor clearColor]];
        }
    }


    return cell;
}

- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
    // Return NO if you do not want the specified item to be editable.
    return YES;
}

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
        [context deleteObject:[self.fetchedResultsController objectAtIndexPath:indexPath]];

        NSError *error = nil;
        if (![context save:&error]) {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        }
    }
}

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath {
    Outgoing *outgoing = [self.fetchedResultsController objectAtIndexPath:indexPath];
    cell.textLabel.text = outgoing.costDescription;
    cell.detailTextLabel.text = [NSString stringWithFormat:@"%.2f",[outgoing.amount floatValue]];

}

Answer 1

可以通过以下方式获取新添加的单元格，前提是新单元格总是添加在最后一个位置。

只需在您的.h 文件中定义标志变量

@property (nonatomic, assign) int addedNewRow;

现在在你的 .m 文件中初始化 addedNewRow 为 -1 就像，

- (void)viewDidLoad {
    [super viewDidLoad];
    self.addedNewRow=-1;
    //other stuff
}

替换下面两个对您的代码有一点增强的方法，

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

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
    [self configureCell:cell atIndexPath:indexPath];

    //UPDATE 1:
    id <NSFetchedResultsSectionInfo> sectionInfo = [self.fetchedResultsController sections][indexPath.section];
    if ([sectionInfo numberOfObjects]-1  == indexPath.row  && self.addedNewRow!=-1) {
        cell.contentView.backgroundColor = [UIColor orangeColor];
        [cell.textLabel setBackgroundColor:[UIColor clearColor]];
    }

    return cell;
}

- (IBAction)insertNewElement:(UIBarButtonItem *)sender
{
    NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
    NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
    Outgoing *outgoing = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];

    // If appropriate, configure the new managed object.
    // Normally you should use accessor methods, but using KVC here avoids the need to add a custom class to the template.
    //[newManagedObject setValue:[NSDate date] forKey:@"timeStamp"];

    // Save the context.

    outgoing.costDescription = expense.costDescription;
    outgoing.amount = [NSNumber numberWithFloat:expense.amount];
    outgoing.date = expense.date;
    outgoing.category = expense.category;


    NSError *error = nil;
    if (![context save:&error]) {
        // Replace this implementation with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    //CHANGES HERE
    self.addedNewRow=0;
    [self.tableView reloadData];
}

希望对你有帮助!!