The TreeMenuView constrol is an animated tree like structured list which enables the user to navigate through different levels of menu items. For now it can only be used by native Xamarin.iOS and Xamarin.Android clients, but Xamarin Forms support is planned as well. Under the hood it is implemented by utilising the power of the UICollectionView on iOS and the RecyclerView on android.

The tree structure of the data is realised by letting your model class implement the Id and ParentId property of the ITreeNodeData<TKey> interface. Now you can pass your data as a flat list to the TreeMenuView.Items property and it will handle the rest.

The layout of the menu item cells is completely custom. You just need to create a subclass of TreeMenuCell<T, TKey>, which itself is a subclass of UICollectionViewCell on iOS and FrameLayout on android.

Install-Package TreeMenuView

If you prefer not to use either of the aforementioned dependency managers, you can integrate TreeMenuView into your project manually.

1. Install package into your application project
2. Create a subclass of ITreeNodeData<TKey> as your data model (see Category.cs)
3. Create some data

var items = new List<Category> {
    new Category(TreeNode.ParentIdNone, 0, "All categories"),
    new Category(parentId:0, id:1, title:"Development"),
    new Category(parentId:0, id:2, title:"Recipes"),
    new Category(parentId:0, id:3, title:"Sport"),
    new Category(parentId:0, id:4, title:"Music"),
    new Category(parentId:0, id:5, title:"Cars"),
    new Category(parentId:1, id:6, title:"Android Development"),
    new Category(parentId:1, id:7, title:"iOS Development"),
    new Category(parentId:3, id:8, title:"Football"),
    new Category(parentId:3, id:9, title:"Formula 1")
};

4. Create a subclass of TreeMenuCell<T, TKey> and implement the setters of its Data and Relation properties (see iOS/CategoryCell.cs and Android/CategoryCell.cs)

• the Data property is your previously created model class
• the Relation property is the relation of the current cell - values are: Root, Parent, Selected, Child

5. Create a TreeMenuView control and apply the items (see ViewController.cs and MainActiviy.cs):

// iOS
var treeMenu = new TreeMenuView<Category, long>(CategoryCell.CellIdentifier, CategoryCell.Height);
treeMenu.RegisterClassForCell(typeof(CategoryCell), CategoryCell.CellIdentifier);
View.AddSubview(treeMenu.View);

treeMenu.Items = items;


// android
var cellHeight = Resources.GetDimensionPixelSize(Resource.Dimension.height_category_cell);
var treeMenu = new TreeMenuView<Category, long>(this, (_,__) => new CategoryCell(this), cellHeight);
layout.AddView(treeMenu.View, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MatchParent, ViewGroup.LayoutParams.MatchParent));

treeMenu.Items = items;

• as you can see you need to provide a specific height for the menu items
• on iOS you need to register the previously created CategoryCell by calling the RegisterClassForCell(...) method
• on android you need to provide a function which creates the CategoryCell

TreeMenuView is released under the MIT license. See the LICENSE file for details.