MVVM架构下iOS添加模型后Cart页面TableView不显示更新数据的问题

Let's break down what's going wrong here and fix it step by step:

1. Immediate Check: Verify Data Reachability in Cart VC #

First, confirm your cart ViewController is actually receiving the populated data:

• In your ViewController (cart VC), add a print statement in tableView(_:numberOfRowsInSection:) to check the row count:

  func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
      let count = chartViewModel.numberOfRowsInSection(section: section)
      print("Number of cart items: \(count)") // Add this line
      return count
  }
  

• If the count is 0 but you confirmed data was added in the add() method, there's a disconnect in how your ViewModel's data is being passed or initialized.

2. Fix ViewModel Data Handling Issues #

Your ViewModel has unnecessary and unsafe code that's causing inconsistencies:

• Remove the redundant line in add():

  func add() {
      guard let newModel = insertedArray else { return } // Replace force unwrap with safe check
      datasourceModel.dataListArray?.append(newModel)
      print(datasourceModel.dataListArray)
      // Delete this line: self.datasourceModel.dataListArray = datasourceModel.dataListArray
  }
  

• Delete the broken insert() method entirely (it tries to insert a String? into a [Model] array, which will cause a compile error):

  // Remove this method
  func insert(){
      add()
      datasourceModel.dataListArray!.insert(insertedArray?.offerdetailAddName, at: indexPath.row)
  }
  

3. Fix IndexPath Bug in HotelViewController #

You're using an undefined indexPath variable in your add-to-cart closure—this is likely causing you to pass incorrect data to the cart model:

cell.cartaddCell = {[weak self] in
    guard let self = self,
          let indexPath = self.tableView.indexPath(for: $0) else { return } // Safe unwrapping
    
    let cartDataSource = DataSourceModel(array: nil)
    let cartViewModel = ViewModel(withdatasource: cartDataSource)
    let cartmodel = Model(withoffermodel: self.offerViewModel.datafordisplay(atindex: indexPath)) // Use the valid indexPath
    
    cartViewModel.insertedArray = cartmodel
    cartViewModel.add()
    
    let cartViewController = ViewController(nibName: "ViewController", bundle: nil, withViewModel: cartViewModel)
    self.navigationController?.pushViewController(cartViewController, animated: true)
}

4. Add MVVM-Compliant Data Update Notifications #

To ensure your TableView refreshes whenever data changes (even for future in-cart updates like deleting items), add a closure to your ViewModel:

• Update your ViewModel class:

  class ViewModel: NSObject {
      var datasourceModel: DataSourceModel
      var insertedArray: Model?
      var finalArray: [Model]? = []
      // Add this closure to notify data changes
      var onDataChanged: (() -> Void)?
  
      init(withdatasource newDatasourceModel: DataSourceModel) {
          datasourceModel = newDatasourceModel
          print(datasourceModel.dataListArray)
      }
  
      // ... existing methods ...
  
      func add() {
          guard let newModel = insertedArray else { return }
          datasourceModel.dataListArray?.append(newModel)
          print(datasourceModel.dataListArray)
          onDataChanged?() // Trigger refresh
      }
  
      func delete(atIndex indexPath: IndexPath) {
          datasourceModel.dataListArray?.remove(at: indexPath.row)
          onDataChanged?() // Trigger refresh
      }
  }
  

• Listen for changes in your cart ViewController:

  override func viewDidLoad() {
      super.viewDidLoad()
      // ... existing setup code ...
      
      // Listen for data changes and refresh TableView
      chartViewModel.onDataChanged = { [weak self] in
          self?.tableView.reloadData()
      }
      
      self.tableView.reloadData()
  }
  

5. Ensure DataSourceModel Initializes a Non-Nil Array #

If your DataSourceModel doesn't initialize an empty array when passed nil, your append calls will silently fail. Fix its initializer:

class DataSourceModel {
    var dataListArray: [Model]?
    init(array: [Model]?) {
        self.dataListArray = array ?? [] // Fallback to empty array if input is nil
    }
}

6. Verify Cell Configuration #

Double-check your ChartCell's setEventData(charts:) method to ensure it's correctly mapping model properties to UI elements:

func setEventData(charts: Model) {
    // Example: Make sure you're setting labels with model data
    nameLabel.text = charts.offerdetailAddName
    priceLabel.text = "\(charts.offerprice)"
    print("Configuring cell with: \(charts.offerdetailAddName)") // Add print to confirm
}

After applying these fixes, your shopping cart TableView should correctly display the added hotel items.

内容的提问来源于stack exchange，提问作者abel