MvvmCross:如何在Android上从常规视图导航到Mvvm视图模型? [英] MvvmCross: How to navigate from regular view to Mvvm viewmodel on Android?

问题描述

我正在将我的应用程序缓慢迁移到Android上的MvvmCross.我还没有将所有Activity都转换为ViewModels.因此，我需要从Mvvm控制的活动导航到常规活动.为此，我创建了自己的Presenter并拦截了Show方法，并执行了自己的StartActivity.那似乎行得通.但是，现在我需要朝另一个方向发展，让我的常规活动返回到原来的Mvvm控制的活动.我尝试仅使用CLEAR_TOP标志在ViewModel上执行StartActivity，但出现错误:

I am slowly migrating my app over to MvvmCross on Android. I have not converted all Activities over to ViewModels yet. Therefore, I need to navigate from an Mvvm-controlled Activity to a regular Activity. To do this, I made my own Presenter and intercepted the Show method and did my own StartActivity. That seemed to work. However, now I need to go the other direction and have my regular Activity go back to the original Mvvm-controlled Activity. I tried just doing a StartActivity on the ViewModel using CLEAR_TOP flag, but I got an error:

"Null Extras seen on Intent when creating ViewModel - this should not happen - have you tried to navigate to an MvvmCross View directly?"

如何从常规活动"返回到Mvvm控制的原始活动?

How can I go back to the original Mvvm-controlled activity from a regular Activity?

推荐答案

简单...

要从任何标准的Android Activity返回，您可以简单地要求Activity使用Finish()

To go back from any standard Android Activity, you can simply ask the Activity to close using Finish()

但除此之外...

如果相反，您想前进到MvvmCross View，那么您需要对MvvmCross内部有一点了解:特别是关于MvvmCross导航在概念上如何在ViewModels之间而不是在Activities，Pages之间发生或UIViewControllers.

If instead you want to go forwards to an MvvmCross View, then you need to know a little about MvvmCross internals: in particular about how MvvmCross navigation conceptually happens between ViewModels rather than between Activities, Pages or UIViewControllers.

如果要前进到新的ViewModel，则可以使用IMvxViewDispatcher单例进行操作-

If you want to go forwards to a new ViewModel, then you can do this using the IMvxViewDispatcher singleton - how to do this is shown in Show view from non-view/viewmodel in mvvmcross

如果随后您想从当前的ViewModel返回，则可以尝试在ViewModel中调用Close(this)-默认情况下，在Android上，它将映射到Finish()，在触摸时会映射到，在WpDev上为GoBack()

If you then later want to go back from the current ViewModel, then you can try calling Close(this) within the ViewModel - by default, on Android this will map to Finish(), on Touch to PopViewController, on WpDev to GoBack()

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