如何删除自定义UICollectionViewCell

Question

I'm really stuck at this one problem. I have a UICollectionView that uses a custom cell (cells are added after user's button press)

Every cell has a button alongside with a few other unrelated controls. When that button is tapped, I want the cell to be deleted.

This is my current problem order:

• User taps a button beneath UICollectionView to enter the ViewController editMode
• User taps a cell and the selected cell enters it's own editMode (not VC editMode)
• User for some reason taps on another cell and gets reminded that only 1 cell is editable at a time
• user presses "ok" and decides to delete the first selected cell by pressing a button subview inside cell A.
• because the user tapped cell B before tapping delete on cell A, the indexPathsForSelectedItems is set to cell B instead of Cell A, causing the user to unfortunately delete the wrong cell.

Deletion code:

- (void)deleteProjects:(NSNotification *)notification {
// Get the current project
NSString *currentProject = [[MyManager sharedManager] projectForDeletion];

[_objects removeObject:currentProject];

[_projectsCollectionView performBatchUpdates:^{

    NSArray *selectedItemsIndexPaths = [_projectsCollectionView indexPathsForSelectedItems];

    // Now delete the items from the collection view.
    [_projectsCollectionView deleteItemsAtIndexPaths:selectedItemsIndexPaths];

} completion:nil];

// Set deleteAlert to NO as we're pretty much done with deleting
deleteAlert = NO;

// Set editedProjects to 0
editedProjects = 0;

// Set deletedProject
deletedProject = currentProject;

// Save the new objects
[[NSUserDefaults standardUserDefaults] setObject:_objects forKey:@"myProjects"];

// Delete the associated subjects if any
[self deleteAssociatedSubjects];

// HERE
[_projectsCollectionView.collectionViewLayout invalidateLayout];
}

Select code:

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:     (NSIndexPath *)indexPath
{
// Get the tapped cell
ProjectCell *projectCell = (ProjectCell *)[collectionView cellForItemAtIndexPath:indexPath];

if (editMode == YES) {
    if (editedProjects == 0) {
        // Set deleteAlert to YES so that we don't mix this UIAlertView
        // with the create project UIAlertView
        deleteAlert = YES;

        // Set editMode to YES for the selected cell
        [projectCell editProject];

        // Prepare the project cell
        projectCell.projectTextField.text = projectCell.projectLabel.text;

        // Set the firstProjectsViewController to YES
        // indicating that the next tapped cell will be second in line
        // in case the user decides to edit a new cell without closing this

        // Set editedProjects to 1
        editedProjects = 1;
    } else if (editedProjects == 1) {
        // Check if the tapped cell is being edited
        if (projectCell.editMode == YES) {
            // Set deleteAlert to YES so that we don't mix this UIAlertView
            // with the create project UIAlertView
            deleteAlert = YES;

            // Set editMode to YES for the selected cell
            [projectCell editProject];

            // Set editedProjects to 0
            editedProjects = 0;

            // Close the keyboard
            [self.view endEditing:YES];

            // Set editedProjects to 0 as we're closing editMode on this cell
            editedProjects = 0;

        } else if (projectCell.editMode == NO) {
            // Tell the user that only 1 project is editable at a time
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Can only edit 1" message:@"You can only edit 1 project at a time" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
            alert.alertViewStyle = UIAlertViewStyleDefault;
            [alert show];
        }
    }
} else {
    // Set the open project
    MyManager *sharedManager = [MyManager sharedManager];
    sharedManager.openProject = nil;
    sharedManager.openProject = @"";
    sharedManager.openProject = _objects[indexPath.item];

    // Open the selected project and dismiss this ViewController
    [self dismissViewControllerAnimated:YES completion:nil];
}
}

Button IBAction (cell code):

- (IBAction)deleteProjectAction:(id)sender {

// Set the projectForDeletion in MyManager
MyManager *sharedManager = [MyManager sharedManager];
sharedManager.projectForDeletion = _projectLabel.text;

// Leave editMode so that we're ready for a new project cell if desired
[self editProject];

// Programatically select this cell
self.selected = YES;

// Tell the ProjectsViewController to delete the project
[[NSNotificationCenter defaultCenter] postNotificationName:@"deleteProject" object:self];
}

In short: how do I delete a custom UICollectionViewCell easily?

I can't describe my happiness and gratitude for help!

THANKS!

Answer 1

使用collectionView:shouldDeselectItemAtIndexPath:可以防止用户取消选择当前处于编辑模式的项目（并且通过不允许多次选择，不应选择被点击的项目，尽管您也可以使用collectionView:shouldSelectItemAtIndexPath: 。

Answer 2

I fixed it by backing up the NSIndexPath when I wanted to and then deleting that. Like this:

didSelectItemAtIndexPath:

    // Set the cellForDeletionIndexPath so that it won't change even though another cell is tapped
    cellForDeletionIndexPath = indexPath;

Deletion code called by a notification sent from cell class (button)

    [_projectsCollectionView performBatchUpdates:^{

    // Now delete the items from the collection view.
    [_projectsCollectionView deleteItemsAtIndexPaths:[NSArray arrayWithObject:cellForDeletionIndexPath]];

} completion:nil];