Placing UIActivityIndicator in a cell when editing UITableViewCell and disabling UserInteraction

When building user interfaces, especially those involving dynamic content updates, it’s common to encounter scenarios where you need to display an activity indicator within a specific cell while the operation is being performed. In this response, we’ll explore how to place a UIActivityIndicator within a UITableViewCell, specifically when editing cells in a UITableView. We’ll also discuss disabling user interaction during this process.

Understanding UITableViewCell and User Interaction

A UITableViewCell is a reusable table view cell that can be customized with various properties, such as its background color, text label, image, or even an accessory view. In the context of our problem, we’re interested in editing cells, which involves displaying a delete button at the end of each row.

User interaction in iOS refers to any action performed by the user on the app’s interface, such as tapping buttons, selecting items from lists, or swiping gestures. Disabling user interaction during an operation ensures that the user cannot inadvertently trigger this operation while it’s being executed.

UIActivityIndicator

The UIActivityIndicatorView is a view component used to display an animation indicating that some work is being performed. It comes in different styles (e.g., white, gray) and can be added as a subview to any other view.

In our scenario, we need to integrate the activity indicator within the cell being edited. This requires understanding how to set its frame and add it to the cell’s hierarchy.

Centering UIActivityIndicator

To center the UIActivityIndicatorView within the cell, we’ll use its frame property to calculate a position based on the cell’s bounds. We’ll then apply these coordinates to the spinner’s frame.

Calculating Center Coordinates

We can calculate the x and y coordinates of the spinner by dividing the cell’s width and height by 2, respectively. This assumes that we want the center of the activity indicator to align with the center of the cell. Here’s a breakdown of the calculation:

CGFloat x = (cell.frame.size.width - spinner.frame.size.width) / 2;
CGFloat y = (cell.frame.size.height - spinner.frame.size.height) / 2;

By using this method, we ensure that the activity indicator is properly centered within its parent view (the cell).

Adding the Activity Indicator

To add the UIActivityIndicatorView to the table view’s hierarchy, we need to make sure it’s a subview of the cell. This can be achieved by adding it directly as a child:

[cell addSubview: spinner];

Subclassing UITableViewCell for Custom Outlets

You may encounter situations where you’re using a custom class for your table view cells, and you need to access specific outlets or properties. In these cases, you’ll typically subclass UITableViewCell and create your own custom outlet definitions.

For example, let’s assume we have a custom cell class called GamesInfoTableViewCell. We might define an outlet like this:

@property (nonatomic, strong) IBOutlet UIActivityIndicatorView *spinner;

With this setup in place, our main code becomes more straightforward:

CommitEditingStyle for UITableViewCell

Now that we’ve covered the basics of adding and centering a UIActivityIndicatorView, let’s discuss how to implement the logic for updating table view cells when editing.

Here’s an example implementation using the standard tableView:commitEditingStyle:forIndexPath: method:

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {

        spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

        UITableViewCell * cell = [tableView cellForRowAtIndexPath: indexPath];
        
        // Setting Frame of Spinner..
        CGFloat x = (cell.frame.size.width - spinner.frame.size.width) / 2;
        CGFloat y = (cell.frame.size.height - spinner.frame.size.height) / 2;

        spinner.frame = CGRectMake(x, y, spinner.frame.size.width, spinner.frame.size.height);

        [cell addSubview: spinner];

        // Start Animating the Activity Indicator
        [spinner startAnimating];
        
        // Perform your Work Here...
    }
}

Disabling User Interaction

To disable user interaction during this operation, we can temporarily set a flag on our cell instance or use an external delegate to control interactions.

Disabling Delete Button

One straightforward approach is to create a temporary flag that indicates whether the cell should be in an editing state. We then check this flag within our tableView:commitEditingStyle:forIndexPath: method:

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete && self.isEditing) {

        // Perform your Work Here...

        [spinner startAnimating];
        
        // Set the flag to false once the animation has completed
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [spinner stopAnimating];
            self.isEditing = NO;
        });
    }
}

With this setup, we can ensure that the delete button remains disabled during the editing process.

Conclusion

By mastering the basics of UIActivityIndicatorView, table view cells, and user interaction, you’ll be well-equipped to tackle complex UI challenges in your iOS development projects. Remember to keep your code organized, use meaningful variable names, and apply standard practices for readability.

Last modified on 2023-11-09