Managing UITableView Cells with UIActivityIndicator and UIProgressView

When working with UITableView cells, especially those that involve data downloads or uploads, it’s common to see a combination of UIActivityIndicator and UIProgressView in the cell’s layout. In this post, we’ll explore how to manage these indicators effectively, reducing performance issues and flickering.

Understanding UITableView Behavior

To understand why reloadData causes performance issues, let’s dive into the behavior of UITableView. When you call reloadData, all cells are completely refreshed, re-assembled, and redrawn. This means that:

1. All subviews of UITableViewCells are removed and re-created.
2. The refresh causes views to flicker or jump back to their start state.

Since there’s no way to set the frame of a UIActivityIndicator, simply restoring some progress value isn’t possible.

Alternatives to ReloadData

Instead of relying on reloadData, which can be costly, let’s explore alternative approaches:

1. Update Individual Elements

When you want to change text within a UITextField or update another element within the cell, no refresh is required. You can simply access the element and set its property.

// Accessing and updating an UITextField
myTextField.text = "New Text";

Similarly, when hiding progress indicators, you can directly access the objects and set their properties:

// Hiding UIActivityIndicator
activityIndicator.hidden = true;

By making these changes, you’re avoiding a complete refresh of the cell. This approach also helps to reduce performance issues associated with reloadData.

2. Designing for Ease of Update

The key here is designing your app so that updates are straightforward and don’t require a full refresh. Consider the following strategies:

• Use data binding or delegate methods to notify your view controller about changes in the data model.
• Implement lazy loading for data retrieval, reducing the number of requests needed.
• Store progress values in a separate object, making it easier to update them.

By designing your app with ease of update in mind, you can avoid the performance issues associated with reloadData.

3. Using an Array of ProgressView References

As suggested by Fernando in the original question, using an array of ProgressView references might seem like a viable solution. However, this approach has its drawbacks:

• It requires additional memory management to keep track of the progress views.
• If not implemented carefully, it can lead to performance issues and flickering.

Before resorting to this approach, make sure you’ve considered the alternatives above and that your design is optimized for updates.

Best Practices

To summarize, here are some best practices for managing UITableView cells with UIActivityIndicator and UIProgressView:

1. Avoid using reloadData: Unless absolutely necessary, use reloadData sparingly to reduce performance issues.
2. Update individual elements: Access and update specific elements within the cell without relying on a full refresh.
3. Design for ease of update: Implement data binding, lazy loading, or other strategies to make updates straightforward.
4. Store progress values carefully: Use separate objects or arrays to store progress values, making it easier to update them.

By following these guidelines and exploring alternative approaches, you can effectively manage UITableView cells with UIActivityIndicator and UIProgressView, reducing performance issues and flickering.

Conclusion

Managing UITableView cells with UIActivityIndicator and UIProgressView requires careful consideration of performance and design. By avoiding unnecessary reloadData calls, updating individual elements, designing for ease of update, and storing progress values carefully, you can create a smooth and efficient user experience. Remember to keep your design optimized for updates, and don’t hesitate to explore alternative approaches if necessary.

## Further Reading

* Apple Developer Documentation: [UITableView](https://developer.apple.com/documentation/uikit/tableview)
* Apple Developer Documentation: [UIActivityIndicator](https://developer.apple.com/documentation/uikit/uiactivityindicator)
* Apple Developer Documentation: [UIProgressView](https://developer.apple.com/documentation/uikit/uiprogressview)

Last modified on 2024-08-14