为MvxTabViewController托管和初始化多个MVVMCross ViewModel [英] Hosting and initialising multiple MVVMCross ViewModels for the MvxTabViewController

问题描述

我需要在iOS中创建一个Tab视图.我试图通过简单地将UITabBar添加到MvxViewController来做到这一点，但是却无法正常工作(请参阅

I need to create a Tab view in iOS. I tried to do this by simply adding a UITabBar to an MvxViewController but I could not get that to work (See this question if interested)

我现在正在尝试使用MVVMCross方法，而Apple似乎将我推向了TabController.

I am now trying to go use the approach MVVMCross and Apple seem to push me towards, a TabController.

在我们的核心项目中，我们有4个ViewModel，它们使用ShowViewModel调用从一个或多个位置显示，并使用customerNumber进行初始化.

In our Core project we have 4 ViewModels that are displayed from one or more places using a ShowViewModel call and are initialised with a customerNumber.

1. CustomerViewModel
2. CustomerOrdersViewModel
3. CustomerHistoryViewModel
4. ReturnsViewModel

在Android和Windows应用商店中，我们为每个这些ViewModel提供了单独的视图.我不想更改我们的Core实现以支持iOS.我将创建一个名为TabbedCustomerViewModel的新ViewModel，它将具有4个属性，每个托管的ViewModels具有一个属性.

In Android and Windows Store we have separate Views for each of these ViewModels. I do not want to change our Core implementation to support iOS. I will create a new ViewModel called TabbedCustomerViewModel and that will have 4 properties, one for each of the hosted ViewModels.

使用在iOS项目中注册的自定义MvxTouchViewPresenter，我可以侦听显示客户"视图之一的请求，然后将请求"切换为TabbedCustomerViewModel.我已经完成了工作，创建了新的ViewModel，并将传递给原始VM的初始化参数传递给了拦截VM的Init方法.

Using a custom MvxTouchViewPresenter registered in the iOS project I can listen for requests to Show one of the Customer views and then switch the Request to TabbedCustomerViewModel. I have that working, the new ViewModel gets created and the initialisation paramaters that would have been passed to the original VM are passed to the intercepting VM's Init method.

我遇到的问题是知道如何初始化托管的VM.我假设我将不得不ctor，init和手动启动它们.有没有人对如何执行此操作有任何想法?

The problem I am having is knowing how I should be initialising the hosted VMs. I assume I am going to have to ctor, init and Start them manually. Has anyone got any thoughts on how to do this?

N- 25 Tab教程不必为此担心，因为其托管的VM不是独立的，因此没有Init和Start依赖项

The N-25 Tab Tutorial does not have to worry about this as its hosted VMs are not standalone so don't have Init and Start dependencies

推荐答案

我也已经初始化了正在运行的VM.当视图加载时，它会通过查看ParentViewController来检查它是否位于选项卡式UI中.

I have the initialisation of the VMs working now too. When the View loads it checks if it is within a Tabbed UI by looking at the ParentViewController.

如果是，它将在新的TabbedCustomerViewModel上调用自定义方法.我已经复制了MVVMCross使用的代码，并将其添加到新的方法中

If it is it calls a custom method on the new TabbedCustomerViewModel. I have copied the code that MVVMCross use and added it to the new Method

try
{
    mvxViewModel.CallBundleMethods("Init", this.initialisationParameters);
    if (reloadedState != null)
    {
        mvxViewModel.CallBundleMethods("ReloadState", reloadedState);
    }
    mvxViewModel.Start();
}
catch (Exception exception)
{
    throw exception.MvxWrap("Problem initialising viewModel of type {0}", mvxViewModel.GetType().Name);
}

TabbedCustomerViewModel在初始化时存储了InitializationParameters和reloadedState，以便可以将其向下传递到其托管的ViewModels

The initialisationParameters and reloadedState are stored by TabbedCustomerViewModel when it is initialised so that it can pass it down to the ViewModels it is hosting

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