Xamarin Picker 选定的项目持久存在于多个页面上 [英] Xamarin Picker selected item persisting on multiple pages
问题描述
问题:也许挑战可以这样表述:如何将内容页面中的单个属性绑定到 Xamarin Forms 中的全局存储变量?
Question: Perhaps the challenge could be stated this way: How do I bind a single property in a content page to a globally stored variable in Xamarin Forms?
详情:我正在使用 MVVM 模式.我有一个带有 Picker 对象的导航内容页面(3 个此类页面中的 1 个)，该对象是从 collectionModel 动态填充的，并且所述模型是读/写的.我试图通过所有 3 个内容页面保留 SelectedItem(或索引，以最合适的方式为准)，以便从页面到页面的导航显示相同的项目(从用户的角度来看).我该怎么做?
Details: I am using the MVVM pattern. I have a navigation content page (1 of 3 such pages) with a Picker object which is populated dynamically from the collectionModel and said model is read/write. I am attempting to persist the SelectedItem (or index, whichever is most appropriate) thru all 3 content pages such that navigation from page to page shows the same item (from the user's perspective). How should I do this?
我可以在 ContentPage_Appearing() 事件中手动设置 Picker.SelectedIndex.我更愿意使用绑定.
I can set the Picker.SelectedIndex manually in ContentPage_Appearing() event. I would much rather use binding.
推荐答案
请按照以下步骤操作:
创建一个静态类，像这样:
Create a static class, like this:
public static class DataClass
{
public static int PickerSelectedIndex = 0;
}
在每个内容页面的ContentPage标记中添加xmlns:local，如下所示:
Add the xmlns:local in ContentPage mark in each Content Page, like this:
xmlns:local="clr-namespace:DataPersist"
在每个页面的 Xaml 中为您的控件绑定数据，如下所示:
Binding the data for your controls in each page's Xaml, like this:
<Picker x:Name="picker" SelectedIndex="{x:Static local:DataClass.PickerSelectedIndex}">
它是这样工作的:
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