C# 带节的MvxCollectionViewController

使用Xamarin.iOS和MvvmCross，我试图创建一个包含节的

MvxCollectionViewController

，每个节包含一个标题和一组

MvxCollectionViewCell

（基于MvvmCross教程）

如本教程所述，我已将

MvxCollectionViewCell

子类化。我有以下模型和ViewModel层次结构（改编自教程）：

每个部分的ViewModel：

public class KittenSectionViewModel : MvxViewModel
{
    private string _sectionName;
    public string SectionName
    {
        get { return _sectionName; }
        set { _sectionName = value; RaisePropertyChanged(() => SectionName); }
    }

    private List<Kitten> _kittens;
    public List<Kitten> Kittens
    { 
        get { return _kittens; }
        set { _kittens = value; RaisePropertyChanged(() => Kittens); }
    }
}

最后，我实现了一个自定义的

MvxCollectionViewSource

，我将其分配给CollectionView的源：

public class KittenCollectionViewSource : MvxCollectionViewSource
{
    KittensViewModel KittensViewModel { get; set; }

    public KittenCollectionViewSource (KittensViewModel kittensViewModel, UICollectionView collectionView, NSString defaultCellIdentifier) : base (collectionView, defaultCellIdentifier)
    {
        this.KittensViewModel = kittensViewModel;
    }

    public override int GetItemsCount (UICollectionView collectionView, int section)
    {
        return KittensViewModel.KittenSections [section].Kittens.Count;
    }

    public override int NumberOfSections (UICollectionView collectionView)
    {
        return KittensViewModel.KittenSections.Count;
    }

    protected override UICollectionViewCell GetOrCreateCellFor (UICollectionView collectionView, NSIndexPath indexPath, object item)
    {
        return collectionView.DequeueReusableCell (DefaultCellIdentifier, indexPath) as KittenCollectionCell;
    }
}

（完整的解决方案可在上获得）

---

问题是，

KittenCollectionCell

需要绑定到一个

Kitten

，但是由于模型被包装在不同的viewmodel中，我不知道如何告诉

MvxCollectionViewSource

使用内部模型

源代码的结构看起来相当简单-因此我认为您缺少的是

GetItemAt

覆盖-请参阅

我认为您需要添加以下内容：

    protected override object GetItemAt(NSIndexPath indexPath)
    {
        if (KittensViewModel == null)
            return null;

        return KittensViewModel
                      .KittenSections[indexPath.Section]
                      .Kittens[indexPath.Row];
    }

您还可以将

KittensViewModel

实现为：

   protected KittensViewModel KittensViewModel { get { return base.ItemsSource as KittensViewModel; } }

---

谢谢@Stuart你是个传奇人物。我曾经在ctor中传递数据源，但不知道我有权访问ItemsSource。你让我开心：）

public class KittenCollectionViewSource : MvxCollectionViewSource
{
    KittensViewModel KittensViewModel { get; set; }

    public KittenCollectionViewSource (KittensViewModel kittensViewModel, UICollectionView collectionView, NSString defaultCellIdentifier) : base (collectionView, defaultCellIdentifier)
    {
        this.KittensViewModel = kittensViewModel;
    }

    public override int GetItemsCount (UICollectionView collectionView, int section)
    {
        return KittensViewModel.KittenSections [section].Kittens.Count;
    }

    public override int NumberOfSections (UICollectionView collectionView)
    {
        return KittensViewModel.KittenSections.Count;
    }

    protected override UICollectionViewCell GetOrCreateCellFor (UICollectionView collectionView, NSIndexPath indexPath, object item)
    {
        return collectionView.DequeueReusableCell (DefaultCellIdentifier, indexPath) as KittenCollectionCell;
    }
}

    protected override object GetItemAt(NSIndexPath indexPath)
    {
        if (KittensViewModel == null)
            return null;

        return KittensViewModel
                      .KittenSections[indexPath.Section]
                      .Kittens[indexPath.Row];
    }

   protected KittensViewModel KittensViewModel { get { return base.ItemsSource as KittensViewModel; } }