关于NSUserDefaults选中行值重存及数组UITableView展示的技术咨询

Hey there! Let's walk through each of your needs with clear, actionable code and explanations:

1. Update NSUserDefaults Value Based on Selected TableView Row #

When the user selects a row in your second ViewController's UITableView, you'll need to fetch the selected entry, update its value, save the modified array back to NSUserDefaults, and refresh the table to show changes. Here's how to do it:

override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    // Grab the selected user entry from the array
    var selectedUser = userInfo[indexPath.row]
    
    // Update the target key-value pair (replace with your actual update logic)
    selectedUser["city"] = "Updated City Name"
    
    // Replace the old entry with the updated one in the array
    userInfo[indexPath.row] = selectedUser
    
    // Save the modified array back to NSUserDefaults
    UserDefaults.standard.set(userInfo, forKey: "userInfo")
    
    // Refresh the specific row to reflect changes
    tableView.reloadRows(at: [indexPath], with: .fade)
}

2. Fix the Array Saving Logic in First ViewController #

Your current code creates a userValue dictionary but doesn't add it to the userArray before saving. Let's correct that to ensure new entries are stored properly:

// Create the user info dictionary safely (no force unwrap needed)
let userValue: [String: String] = [
    "name": self.nameLbl.text ?? "",
    "lastName": self.lastNameLbl.text ?? "",
    "city": cityLbl.text ?? ""
]

// Fetch existing array from UserDefaults (or initialize empty if none exists)
var userArray = UserDefaults.standard.array(forKey: "userInfo") as? [[String: String]] ?? []

// Add the new user entry to the array
userArray.append(userValue)

// Save the updated array back to UserDefaults
UserDefaults.standard.set(userArray, forKey: "userInfo")

// Optional: For pre-iOS 10 versions, you can call synchronize (not required for modern iOS)
// UserDefaults.standard.synchronize()

Note: Avoid using as! here—it can cause crashes if type casting fails. Explicitly defining the dictionary type [String: String] is safer.

3. Complete the UITableView Display in Second ViewController #

To fully show the userInfo array in your table view, you need to load the data from UserDefaults and implement the required UITableView DataSource methods. Here's the full implementation:

class SecondViewController: UIViewController, UITableViewDataSource {
    var userInfo = [[String:String]]()
    @IBOutlet weak var tableView: UITableView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Load saved data from UserDefaults
        if let savedUsers = UserDefaults.standard.array(forKey: "userInfo") as? [[String: String]] {
            userInfo = savedUsers
        }
        
        // Set the table view's data source
        tableView.dataSource = self
        
        // Register a default cell (replace with your custom cell if needed)
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "UserInfoCell")
    }
    
    // MARK: - UITableView DataSource Methods
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return userInfo.count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "UserInfoCell", for: indexPath)
        let currentUser = userInfo[indexPath.row]
        
        // Format cell content to display user info (customize this to your needs)
        cell.textLabel?.text = "\(currentUser["name"] ?? "") \(currentUser["lastName"] ?? "")"
        cell.detailTextLabel?.text = "City: \(currentUser["city"] ?? "")"
        
        return cell
    }
}

If you're using a custom UITableViewCell, replace the default cell registration and configure your custom cell's outlets instead of using textLabel/detailTextLabel.

内容的提问来源于stack exchange，提问作者Nazar