Why can't a cell example be recorded?

An example of a cell in the context of iOS development is usually called a prototype (prototype) of a cell in Interface Builder or in code. The prototype describes the appearance and behavior of the cell.

• You cannot directly write a cell instance to a file or save its state because:

  • Cells (UITableViewCell, UICollectionViewCell) are UI elements and are closely tied to their view hierarchy and the UIKit (or SwiftUI) framework lifecycle.
  • They contain references to other UI elements (UILabel, UIImageView, etc.) and handle UI events. Serialization of these objects to a file (e.g., via NSCoding or Codable) is not fully supported, as such objects are not meant to be stored outside the application context and UI hierarchy.
  • The appearance and data of a cell change dynamically depending on the data source and delegate of the table or collection view during scrolling. iOS reuses cell instances for performance optimization, constantly updating them. Saving a specific instance makes little sense because it is a temporary representation of data at a certain moment.

• You can save the description of a cell, which includes:

  • Its class (UITableViewCell or UICollectionViewCell).
  • The reuse identifier (reuseIdentifier).
  • The structure of subviews and their constraints/frames.
  • Appearance settings (color, font, etc.).

This description is used to create a new instance of a cell when needed, not to restore an existing one. Prototypes in storyboards/xibs or custom cell classes with a setupViews() method are exactly such descriptions.

For example, when registering a cell for a table view:

// Registering a cell class by id
tableView.register(CustomCell.self, forCellReuseIdentifier: "customCellId")

or

// Using a XIB file
let nib = UINib(nibName: "CustomCell", bundle: nil)
tableView.register(nib, forCellReuseIdentifier: "customCellId")

Then, when requesting a cell:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    guard let cell = tableView.dequeueReusableCell(withIdentifier: "customCellId", for: indexPath) as? CustomCell else {
        fatalError("Unable to create CustomCell")
    }
    // Configure the cell based on data
    let item = data[indexPath.row]
    cell.configure(with: item)
    return cell
}

The system either creates a new instance of CustomCell based on the registered description or returns a reusable instance, which is then configured. The cell instance itself is not saved between sessions or outside the context of the table/collection.