Xamarin MVVM 交叉绑定 MVXtableViewCell

Question

我是 MVVMCross 的新手。我正在通过子类化 MVXTableVIewCell 创建自定义表格视图单元格。我在单元格中有一个删除按钮。当用户单击删除按钮时，将从表中删除相同的记录。我不确定如何将单元格中的删除按钮绑定到视图模型类。下图是 ViewModel 类、Custom cell 类和 RelayCommand 类。

public class DebriefViewModel: MvxViewModel, INotifyPropertyChanged
{
   public RelayCommand DeleteDebriefCommand { get; set; }
   public DebriefViewModel()
   {
     DeleteDebriefCommand = new RelayCommand(DoDeleteDebrief);
   }
   public async void DoDeleteDebrief(object param)
   {
      Debrief debriefDelete = (Debrief)param;
     //Code to delete the debrief.
    }
 }

public partial class DebriefViewCell : MvxTableViewCell
{
    public static readonly UINib Nib = UINib.FromName("DebriefViewCell", NSBundle.MainBundle);
    public static readonly NSString Key = new NSString ("DebriefViewCell");

    public DebriefViewCell (IntPtr handle) : base(BindingText,handle)
    {
        this.DelayBind(() => {
          var set = this.CreateBindingSet<DebriefViewCell, DebriefViewModel>();
          //Not sure how to bind the deleteDebriefBttn
          set.Bind(deleteDebriefBttn).To(vm => vm.DeleteDebriefCommand);
          set.Apply();
        });
    }

   public static DebriefViewCell Create ()
   {
       return (DebriefViewCell)Nib.Instantiate (null, null) [0];
   }
 }

public class RelayCommand : ICommand
{
    // Event that fires when the enabled/disabled state of the cmd changes
    public event EventHandler CanExecuteChanged;

    // Delegate for method to call when the cmd needs to be executed        
    private readonly Action<object> _targetExecuteMethod;

    // Delegate for method that determines if cmd is enabled/disabled        
    private readonly Predicate<object> _targetCanExecuteMethod;

    public bool CanExecute(object parameter)
    {
        return _targetCanExecuteMethod == null || _targetCanExecuteMethod(parameter);
    }

    public void Execute(object parameter)
    {
        // Call the delegate if it's not null
        if (_targetExecuteMethod != null) _targetExecuteMethod(parameter);
    }

    public RelayCommand(Action<object> executeMethod, Predicate<object> canExecuteMethod = null)
    {
        _targetExecuteMethod = executeMethod;
        _targetCanExecuteMethod = canExecuteMethod;
    }

    public void RaiseCanExecuteChanged()
    {
        if (CanExecuteChanged != null) CanExecuteChanged(this, EventArgs.Empty);
    }
}

我不知道如何将我的 DebriefViewCell 中的“deleteDebriefBttn”绑定到 DebriefViewModel 中的 DeleteDebriefCommand。请帮帮我。

Answer 1

在 TableSource 构造函数中传递 ViewModel 引用，然后在 CommitEditingStyle 覆盖中使用此 ViewModel 的命令。

public override void CommitEditingStyle(UITableView tableView, UITableViewCellEditingStyle editingStyle, NSIndexPath indexPath)
        {
            switch (editingStyle)
            {
                case UITableViewCellEditingStyle.Delete:
                    viewModel.RemoveCommand.Execute(indexPath.Row);
                    break;
            }
        }