Repository with some additional classes and extensions for the Prism Library for Xamarin Forms.

Package name	Nuget
Zaggoware.Prism.Forms
Zaggoware.Prism.Forms.Navigation
Zaggoware.Prism.Forms.ViewModels

To make navigation easier and better structured instead of using hardcoded strings, a navigation builder has been added. Use the extension method Builder() or Builder<TBuilder>() in Zaggoware.Prism.Forms.Navigation on Prism's NavigationService to create a new builder:

INavigationBuilder builder = NavigationService.Builder();

await NavigationService
    .Builder()
    .FromRoot()
    .ToPage<MainPage>()
    .NavigateAsync()
// This results in: "/MainPage"

.FromRoot() can be useful when the user is not allowed to navigate back (e.g. when logging out).

Going to a (sub-)page with navigation history:

await NavigationService
    .Builder()
    .ToPage<NavigationPage>()
    .ToPage<DetailsPage>()
    .WithId(123)
    .NavigateAsync();
// This results in: "NavigationPage/DetailsPage?Id=123"

To add navigation parameters:

await NavigationService
    .Builder()
    .ToPage<NavigationPage>()
    .ToPage<AnotherPage>()
    .WithParam("Foo", "Bar") // Tip: ParamNames.Foo (see tip below) or extension method: WithFoo(...)
    .WithParam("Bar", "Foo") // Tip: Paramnames.Bar (see tip below) or extension method: WithBar(...)
    .NavigateAsync();
// this results in: "NavigationPage/AnotherPage?Foo=Bar&Bar=Foo"

Tip: To prevent hardcoding the param names, create a class named ParamNames and add constant strings to it. When retrieving the parameters, you can then simply call parameters.GetValue<string>(ParamNames.Foo). Or even better, create an extensions class so you can call parameters.GetFoo().

By default, page navigation has an animation. To disable this, you can add Animate(false) to the builder:

await NavigationService
    .Builder()
    .ToPage<NavigationPage>()
    .ToPage<AnotherPage>()
    .Animate(false)
    .NavigateAsync();

For modal windows, you can simply add AsModal() to the builder:

await NavigationService
    .Builder()
    .ToPage<MyModalPage>()
    .AsModal()
    .NavigateAsync();

By default, the builder does not throw exceptions when navigation failed. This is the same behavior as Prism. To force exceptions, you can add EnsureSuccess() to the builder:

await NavigationService
    .Builder()    
    .ToPage<NavigationPage>()
    .ToPage<AnotherPage>()
    .EnsureSuccess()
    .NavigateAsync();

Alternatively, you can set a global failure handler with the static NavigationBuilder.NavigationFailedHandler property. Note that EnsureSuccess() will only throw after the handler is called.

The NavigationBuilder class implements INavigationBuilder and all methods are made virtual. This means you can easily derive from the default builder class and override a method without losing any functionality. To access your custom navigation builder, simply call the extension method Builder<TBuilder>() where TBuilder is the type of your custom builder. This method supports additional constructor arguments if required.

For your convience, a state service has been built-in which will keep track of the last navigated page, including its navigation parameters. Every time NavigateAsync() is called on the NavigationBuilder, this state will be updated. This can come in handy when other dependencies need to know the current page and/or its parameters. The state service is a singleton and can be accessed by its static instance property: NavigationStateService.Instance.

The state service contains three properties:

• LastNavigationParams containing the navigation parameters of the last navigation.
• LastNavigationUri containing the URI if available. This can be set with the builder by using WithUri(Uri uri), replacing the ToPage<TPage>() routing.
• LastNavigationRoute containg the route of the last navigation (e.g. "/MainPage/NavigationPage/DetailsPage")

Known issue: When navigating back (NavigationService.GoBackAsync()) the state is not automatically updated.