Since MAUI's Shell navigation is a bit castrated and not suitable with building production-ready large applications and, unfortunately, Prism Library for .NET MAUI has some critical (for our company) bugs and different behavior comparing to Prism.Forms and since Prism became paid, we decided to write our own navigation framework. This library brings you the same principle for navigation through the MAUI app as Prism, but has absolutely different implementation and a bit improved performance. It also brings (in our opinion) proper way to handle 'System back button' click, it works and has same behavior for all platforms.
This is the core library for MPowerKit.Navigation and other libraries. It contains core functionality, utility classes and interfaces.
Awares
Same as in Prism, aware interfaces are here to know when and what page event happens. For your page / viewmodel to be awared for particular event it should implement that aware interface.
It has only one interface method void Initialize(INavigationParameters parameters);.
This method is executed right after the page and it's viewmodel has been created and not attached to visual tree. Executes for each page in navigation stack continuously in direct order. Accepts INavigationParameters as input arguments. Executed only once during the lifetime of the page.
If you want your page or it's viewmodel know about this event, it must implement this interface.
It's purpose to get INavigationParameters and probably to subscribe to some events.
Note: There is no IInitializeAsyncAware interface, because in mobile development it is not a good practise calling async methods when your page is not atatched to visual tree
It has only one interface method void Desctroy();.
This method is executed right after the page and it's viewmodel has been detached from visual tree and needs to be GCed. Executes for each page in navigation stack continuously in reverse order. Executed only once during the lifetime of the page.
If you want your page or it's viewmodel know about this event, it must implement this interface.
It's purpose to unsubscribe from events and clear resources.
void OnNavigatedFrom(INavigationParameters parameters);. This method is executed when the forward or backward navigation from the page happens.
When a new page is opened this event will be called on a previous page with NavigationDirection parameter included with the NavigationDirection.New value.
When going back this event will be called on a page is being closed with NavigationDirection parameter included with the NavigationDirection.Back value.
void OnNavigatedTo(INavigationParameters parameters);. This method is executed when the forward or backward navigation to the page happens.
When a new page is opened this event will be called on a new page with NavigationDirection parameter included with the NavigationDirection.New value.
When going back this event will be called on a previous page in the stack with NavigationDirection parameter included with the NavigationDirection.Back value.
To get NavigationDirection value you can call GetNavigationDirection() extension method on INavigationParameters variable;
This interface is tied to the Page class lifecycle events
It has two interface methods:
void OnAppearing();. This method is executed when the page is appearing.
void OnDisappearing();. This method is executed when the page is disappearing.
Note: This interface should be implemented only by page viewmodels, because Page class already has these methods under the hood from MAUINote: You can get page lyfecycle events in the regions if region views / viewmodels implement this interface
If you want to have the full control over the navigation process you would want your page or it's viewmodel implement this interface.
It has only one interface method bool OnSystemBackButtonClick();. This method is executed when the system back button was clicked. It works on all platfroms, supported by MAUI, even on iOS and MacCatalyst, even when a page is closed by swipe.
It returns boolean value indicating whether this event was handled or not. If handled, then the backward navigation should be handled by developer, eg call INavigationService.GoBackAsync(). If not, the backward navigation will be handled by the MAUI itself. In this case no navigation or destructive events are called by MPowerKit.
This interface has only one boolean property bool IsOnActiveTab { get; set; } indicating the tab page is active or not.
This interface can be implemented by the page which is the root of the tab. If the root of the tab is NavigationPage the IsOnActiveTab property will be changed on this NavigationPage and on RootPage and CurrentPage of this NavigationPage if they are implementing this interface.
Note: It will take no effect if this property is changed manually from the tab page / viewmodel
This interface has only one boolean property bool IsFlyoutPresented { get; set; } indicating the Flyout is presented or not.
This interface can be implemented by the FlyoutPage viewmodel, Flyout page, Detail page. If the root of the Detail page is NavigationPage the IsFlyoutPresented property will be changed on this NavigationPage and on RootPage and CurrentPage of this NavigationPage if they are implementing this interface.
Note: It will take no effect if this property is changed manually from the FlyOut page / viewmodel
This class is used as a return type of each navigation. It contains information about was navigation successful or not and if not it will contain an exception with error description.
This is a generic base class for all behaviors you may use in your MAUI app. It has the same BindingContext as the control it attached to, so you can easily bind to your viewmodel from behavior.
This is a static class which contains methods for registering and resolving views for navigation. You may register pages as well as regular views (used by regions) for navigation.
This is a static class which contains methods for registering behaviors and associating them with views. Then registered behaviors will be applied to the associated view, when this view created by the library.
Note: The associated views should be registered for navigation if you want the behaviors be applied to these views
Since under the hood ConfigureServices() method uses IServiceCollection object of MauiAppBuilder you can also register your services outside ConfigureServices method.
But it is way better to keep all of your registrations in one place.
There is already registered a bunch of neccessary services used by this library. The entire list you can find here.
But there is some services you may need to extend or completely change registration.
MPowerKitWindow is registered as transient service as IMPowerKitWindow and gives an ability to handle system back button click and window lifecycle.
If you need to change MPowerKitWindow implementation or change the system back button click behavior you can extend this class and register new implementation as next:
NavigationService is registered as scoped service as INavigationService. It is used for navigation through the app. The detailed descriptions is here.
If you need to override some basic implementations of it, you can register your implementation as next:
NavigationPage. Note: For iOS and MacCatalyst custom navigation page renderer is registered to handle iOS/mac title bar back button click and swipe-to-close events.
TabNavigationPage. You may use it as root page of TabbedPage tab. It has logic to pass the icon and title from it's root page to TabbedPage.
OnAppStart() executes when the app is ready to navigate to the first page. This is required method, without it the app will crash on the start. This is async method
When you specify .UsePopupNavigation() it registers MPowerKitPopupsWindow as main class for every window, it is responsible for system back button.
It inherits MPowerKitWindow which is main class for window in MPowerKit.Navigation, it also responsible for system back button on every platform, even in mac and ios (top-left back button on the page's toolbar)
To have full control over the popup flow it is better that your popup or popup's viewmodel implement this interface. This interface gives you an ability to close popup programmatically from popup or it's viewmodel.
IPopupDialogAware interface provides only one property RequestClose. It is an Action. You should call it when you want to close the popup. It accepts a tuple with Confirmation object and a boolean whether animated or not.
The value for RequestClose property is set under the hood by the framework, so you don't need to do smth extra with it.
Confirmation is a record which accepts 2 parameters:
Boolean whether confirmed or not;
INavigationParameters to pass the parameters back from popup to popup caller (it is optional).
Example
public class TestPopupViewModel : IPopupDialogAware
{
public Action<(Confirmation Confirmation, bool Animated)> RequestClose { get; set; }
protected virtual async Task Cancel(object obj = null)
{
var nparams = new NavigationParameters
{
{ NavigationConstants.CloseParameter, obj }
};
RequestClose?.Invoke((new Confirmation(false, nparams), true));
}
protected virtual async Task Confirm(object obj = null)
{
var nparams = new NavigationParameters
{
{ NavigationConstants.CloseParameter, obj }
};
RequestClose?.Invoke((new Confirmation(true, nparams), true));
}
}
Main unit of work of this library is IPopupNavigationService. Under the hood it is registered as scoped service (NOT SINGLETONE), which means that it knows from which page it was opened to know the parent window it is attached to.
So, in theory you can open different popups in different windows in same time.
Inject IPopupNavigationService to your page's or viewmodel's contructor.
When you invoke this method it will show the popup and the main thread will continue doing it's very important work.
You can provide close callback which accepts Confirmation object with boolean whether confirmed or not and INavigationParameters parameters.
it invokes all necessary aware interfaces you specified for your popup or it's viewmodel.
The result of showing popup is NavigationResult
When you invoke this method it will show the popup and it will await until the popup is closed.
The reslut of this method is PopupResult. PopupResult is inherited from NavigationResult. It has extra property for Confirmation object to know how the popup was closed.
Hides the specified popup if it was opened.
The difference with MPowerKit.Popups that it invokes all necessary aware interfaces you specified for your popup or it's viewmodel.
MPowerKit.Navigation.Regions
Like MPowerKit.Navigation Regions library is very similar to Prism's one. It has same sense, but different implementation.
Shortly what it is:
In MAUI you can navigate only through pages, but what if you need to have big page with few different sections, let's call them, regions. For example: TabView or some desktop screen with sections. Do we need to keep all logic in one god viewmodel? - With regions no.
It gives you simple and flexible way to navigate to the regions (sections on UI) from your page or viewmodel, or even from another region. Each region can hold as much views as you like, but only one will be visible at the moment. And you can simply put all logic related to the section inside the region viewmodel. Regions can be recursive.
Setup
Add UseMPowerKitRegions() to your MauiProgram.cs file as next
Note: if you are using regions in couple with MPowerKit.Navigation you can specify whether you want your region views get parent page's events like navigation, destroy, lifecycle etc.
Just add UsePageEventsInRegions() to mpowerBuilder
This is very helpful if you use it, for example, with TabView and you need to open new tab with tab specific dynamic data which has region(s). With static names you are not able to do such trick.
!!! Important: the region names MUST be unique throughout the entire app or it will crash!!!
To remove region holder from region registrations there is hidden method RegionManager.RemoveHolder(string? key).
Performs navigation within an empty region holder. It creates an IRegion object that describes the region with a region stack and then pushes the chosen view into the region. If the region holder already contains child views, it will clear the region stack and push the new view into the region.
Retrieves all child regions associated with a chosen region holder. It can be particularly useful when you need to clean up resources and invoke lifecycle events for these regions.
To use IRegion object just inject it to your region view ot it's viewmodel and then you will have the control over your region stack.
This interface is registered as scoped service. It means that each region holder contains it's own IRegion object which can be injected into each region view it holds. This object is responsible for navigation inside the region it describes.
Each region has it's region stack and CurrentView. Region stack is just Grid with children. So it means that all of region views are currently attached to the visual tree but only one is visible. Visible region view is CurrentView.
Checks whether it can navigate back through the region stack.
Can go forward
bool CanGoForward();
Same as CanGoBack but to the opposite direction.
Also, this interface describes another few utility methods which invoke aware interfaces.
Region views or their viewmodels can implement next aware interfaces: IInitializeAware, INavigationAware, IDestructible, IWindowLifecycleAware, IPageLifecycleAware
