Xamarin形成MVVM Stacklayout内容绑定 [英] Xamarin forms MVVM Stacklayout content binding

问题描述

我真的是Xamarin和Xamarin表格的新手，我需要一些帮助.

I'm really new to Xamarin and Xamarin forms and I need some help.

我有一个StackLayout，我想从ViewModel动态地向其中添加项目.问题是我似乎无法将StackLayout的内容绑定到ViewModel的StackLayout.

I have a StackLayout to which I want to add items dynamically from my ViewModel. Problem is I can't seem to bind the content of the StackLayout to my ViewModel's StackLayout.

这是我看来的xaml代码

this is my xaml code in my view

<StackLayout/>

我想要

<StackLayout Content="{Binding MainStackLayout}"/>

我已经在ViewModel中设置了这样的StackLayout

I have a StackLayout already setup in my ViewModel like this

public StackLayout MainStackLayout;

推荐答案

您必须编写一个UI组件.

You have to write a UI component.

using Xamarin.Forms;

using System.Collections.Specialized;
using System.ComponentModel;

class BindableStackLayout : StackLayout
{
    public static readonly BindableProperty ItemsProperty =
        BindableProperty.Create(nameof(Items), typeof(ObservableCollection<View>), typeof(BindableStackLayout), null,
            propertyChanged: (b, o, n) =>
            {
                (n as ObservableCollection<View>).CollectionChanged += (coll, arg) =>
                {
                    switch (arg.Action)
                    {
                        case NotifyCollectionChangedAction.Add:
                            foreach (var v in arg.NewItems)
                                (b as BindableStackLayout).Children.Add((View)v);
                            break;
                        case NotifyCollectionChangedAction.Remove:
                            foreach (var v in arg.NewItems)
                                (b as BindableStackLayout).Children.Remove((View)v);
                            break;
                        case NotifyCollectionChangedAction.Move:
                            //Do your stuff
                            break;
                        case NotifyCollectionChangedAction.Replace:
                            //Do your stuff
                            break;
                    }
                };
            });


    public ObservableCollection<View> Items
    {
        get { return (ObservableCollection<View>)GetValue(ItemsProperty); }
        set { SetValue(ItemsProperty, value); }
    }
}

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