如何持久化自定义UINib数组拖拽重排后的顺序？

Hey there! Let's get your drag-reorder and persistence working smoothly. The key here is that you can't directly save UINib instances to persistent storage, so we'll work with cell identifiers instead, then map those back to UINib objects when needed. Here's a step-by-step breakdown:

Step 1: Add Unique Identifiers to Your Cell Classes #

First, give each custom cell a static identifier (match it to your nib filename for consistency):

import UIKit
class TestCell1: UITableViewCell {
    static let identifier = "TestCell1" // Unique identifier matching your nib name
    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }
}

// Repeat this pattern for your other two cell classes
class TestCell2: UITableViewCell {
    static let identifier = "TestCell2"
    override func awakeFromNib() {
        super.awakeFromNib()
    }
}

class TestCell3: UITableViewCell {
    static let identifier = "TestCell3"
    override func awakeFromNib() {
        super.awakeFromNib()
    }
}

Step 2: Adjust Your Global Array to Store Identifiers #

Instead of storing UINib instances directly, use a global array of strings (these identifiers will be our persistent data):

// Global array (or use a singleton for cleaner architecture if you prefer)
var cellOrderIdentifiers: [String] = [TestCell1.identifier, TestCell2.identifier, TestCell3.identifier]

Add a helper function to convert these identifiers back to UINib instances when you need them for your table view:

func loadNibsForCurrentOrder() -> [UINib] {
    return cellOrderIdentifiers.map { UINib(nibName: $0, bundle: nil) }
}

Step 3: Implement Drag-Reorder in Your Table View #

Add the table view delegate methods to enable dragging and update the array order when a row is moved:

extension YourTableViewController: UITableViewDelegate {
    // Allow all rows to be moved
    func tableView(_ tableView: UITableView, canMoveRowAt indexPath: IndexPath) -> Bool {
        return true
    }

    // Handle the row move and update our identifier array
    func tableView(_ tableView: UITableView, moveRowAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {
        // Update the global identifier array to match the new order
        let movedIdentifier = cellOrderIdentifiers.remove(at: sourceIndexPath.row)
        cellOrderIdentifiers.insert(movedIdentifier, at: destinationIndexPath.row)
        
        // Save the new order immediately to persistence
        persistCellOrder()
        
        // Optional: Reload the table if you need to reflect any UI changes right away
        tableView.reloadData()
    }
}

Make sure your table view's delegate is set to your view controller!

Step 4: Persist the Order with UserDefaults #

Add functions to save and load the cell order using UserDefaults—it's lightweight and perfect for this use case:

func persistCellOrder() {
    UserDefaults.standard.set(cellOrderIdentifiers, forKey: "SavedCellOrder")
}

func loadPersistedCellOrder() {
    if let savedIdentifiers = UserDefaults.standard.array(forKey: "SavedCellOrder") as? [String] {
        cellOrderIdentifiers = savedIdentifiers
    }
    // If no saved order exists, we'll fall back to the default initial order
}

Call loadPersistedCellOrder() when your app starts (like in viewDidLoad() of your table view controller) to restore the last saved order:

override func viewDidLoad() {
    super.viewDidLoad()
    loadPersistedCellOrder()
    // Other setup code...
}

Why This Works #

We use identifiers instead of UINib instances because UINib isn't serializable for persistent storage. Storing strings is lightweight, reliable, and easy to map back to the UINib objects you need for your table view.

内容的提问来源于stack exchange，提问作者Michael