Introduction

In iOS development, the `UITableViewCell` is a fundamental component used to display a single row of data in a `UITableView`. A common issue that developers encounter is when a `UITableViewCell` remains highlighted or selected even after its intended action has been completed. Understanding why this occurs and how to manage it effectively is crucial for creating a smooth user experience. This article provides an in-depth explanation and solution strategies for handling `UITableViewCell` highlighting issues.

How Highlighting Works

The Highlighting Mechanism

When a user taps a cell in a `UITableView`, the `UITableView` undergoes a series of actions:

1. The cell is highlighted immediately to provide visual feedback. This is managed by the method `setHighlighted(_:animated:)`.
2. The table view delegate method `tableView(_:didSelectRowAt:)` is called, where any specific action for that row can be executed.
3. After the method returns, the cell may remain in its highlighted state or be deselected based on additional configurations.

Default Behavior

By default, a table view handles cell deselection by removing the highlight as soon as the user lifts their finger. However, if there's any delay or failure in deselecting the cell, it will remain highlighted.

Technical Reasons for Persistent Highlighting

Event Handling Delays

One technical reason for persistent highlighting can be delays in the event-handling loop. If the logic inside `tableView(_:didSelectRowAt:)` involves expensive computations or networking requests, the user interface may not get the chance to perform deselection smoothly.

Asynchronous Tasks

If an asynchronous task is triggered on cell selection, such as a server call with a completion handler, without appropriately processing user interface updates within the main thread, the cell might remain highlighted until the asynchronous task completes.

Improper Use of Selection Style

Another possibility could be due to not setting the cell's `selectionStyle` correctly. If the `UITableViewCell`'s `selectionStyle` is set to `.none`, it will prevent normal selection appearance and animations, potentially causing confusion.

Code Example

Here’s a simple code example demonstrating how to handle the persistent highlighting issue using asynchronous requests: