I have a ReactiveContentPage with several ReactiveChildViews. One Problem that I still not solved satisfying is how to forward the whenActivated event to my child views as Xamarin Forms Views do not support an OnAppearing event that is neessary for .whenActivated to work.
Related
I need a ListView with long pressed event handler.
When listviewItem is longpressed, an popup should appear for example.
Does anyone knows, if this is possible with xamarin.forms MVVM?
Thanks
There is a known issue about this in xamarin forms, you can check it here: [Enhancement] LongPressGestureRecognizer.
And just as this remark mentioned :
this will probably be in .NET MAUI but won't make it into
Xamarin.Forms anymore. If needed check out the Xamarin Community
Toolkit or other relevant libraries
But there are several workarounds:
You can refer to article: Longpress Event For Image In Xamarin.Forms.
And you can also check thread : How to make long press gesture in Xamarin Forms?
I am implementing Prism in a new Xamarin Forms App. I have been using Rg.Plugins.Popup in the app before converting to Prism.
What are the limitation on the Prism Dialogs vs Prism.Plugin.Popups?
What are some examples when you would use one over the other?
Thank you!
Rg.Plugins.Popup is a popular plugin for Xamarin.Forms which accesses the native functionality to provide a "Modal Popup" which traditionally has not been achievable with Xamarin.Forms.
Dialogs in Prism 7.2
If you're using Prism 7.2 you'll find that the DialogService locates the currently displayed page and then "reparent's the content". Or in other words it takes the content of the active Content Page and places it as the root child of an AbsoluteLayout, placing a mask layer and finally your dialog on top. As a result of this approach you'll notice that any navigation bars for instance on the NavigationPage or TabbedPage, or a MasterDetailPage's menu will remain accessible to the user.
While in some regard both the PopupPage and Dialog may look very similar as you can probably tell there is some significant divergence there.
Dialogs in Prism 8
If you're using Prism 8.0 you'll see that we have updated to the latest Xamarin.Forms and as a result we are able to take advantage of a new feature in Xamarin.Forms which allows you to present a Modal Page with a Transparent background. This in effect allows you to replicate the effect of a PopupPage with either some benefits or drawbacks depending on how you look at it.
With Rg.Plugins.Popups you have the ability to push a PopupPage on top of whatever page is currently displayed from anywhere in the app
With Xamarin.Forms page's that have been pushed Modally they are part of your active Navigation Stack
Using the a traditional page with a transparent background and Modal Navigation you in effect have replicated the appearance of what you get with a PopupPage
Limitations
Prism.Plugin.Popups has the benefit of being integrated into the Navigation Service. As such you can inject the Navigation Service into the ViewModel of a PopupPage, and the PopupPage will be dismissed when you navigate away from it to another non PopupPage.
Dialogs are not part of the Navigation Stack tracked by Prism's Navigation Service. Navigation in Xamarin.Forms is dependent on navigating FROM a specific page. Since Prism's NavigationService doesn't know about the Dialog you will need to dismiss the dialog before navigating.
Other Key Differences
Besides what I've mentioned so far the only real difference is that Rg.Plugins.Popup gives you some added animations which honestly I've seen very few people using.
When I open TabbedPage from another TabbedPage in Xamarin.Forms for iOS the right part of bottom bar has that strange glitch/blink. Is there any solution to fix it?
There might be a need to reconsider UX in the app you are working on. Nested tabs are not intuitive and very confusing, beside the technical issues you can run into, here is a summary of notes from the official Xamarin.Forms docs:
It's recommended that a TabbedPage should be populated with
NavigationPage and ContentPageinstances only. This will help to ensure
a consistent user experience across all platforms.
The TabbedPage does not support UI virtualization. Therefore,
performance may be affected if the TabbedPage contains too many child
elements.
While it's acceptable to place a NavigationPage into a TabbedPage,
it's not recommended to place a TabbedPage into a NavigationPage. This
is because, on iOS, a UITabBarController always acts as a wrapper for
the UINavigationController. For more information, see Combined View
Controller Interfaces in the iOS Developer Library.
I want to create custom Tabbar in Xamarin Forms using NaviagtionPages & Buttons added inside a ContentPage.
I cannot use the default Tabbed Page because the UI shows up differently for Android and iOS with it (tabbar at top on android vs tabbar at bottom for iOS).
Hence, I was creating a common component using Xamarin forms.
I have created a similar custom tabbar in iOS (by adding Navigation controllers as child controllers along with buttons in a View controller).
So far I have added Buttons and ContentPages(by ContentPage.Content) inside a ContentPage. I toggle the visibility of the content pages on tapped events of the buttons.
But I want to replace the ContentPages by NavigationPages so that each tab(button) can have its own stack of ContentPages.
Unfortunately, I cannot figure out how to add NavigationPage inside a content view to make this work.
I’m working on an application for Android and iOS, which requires a certain flexibility for one or two views. That’s why we created & implemented a service that translated a basic list of objects into a user interface for both iOS & Android. But now that Xamarin.Forms is released, we decided to replace our service by the one Xamarin provides. I did succeed in creating the views with Xamarin.Forms, resulting in better looking & smoother running pages. But my problem lies in the navigation of it. Here is a little drawing on what I would like to achieve:
I would like my app to start an activity that starts with a custom fragment. After clicking a button on this fragment, I would like the page I created with the Xamarin.Forms api to be added to my current navigation stack! Once the user is finished with the Xamarin.Forms page, it navigates to a second custom fragment, all that without breaking the navigation cycle. Does anybody have an idea on how I can achieve this?
For the iOS developpers: replace Activity with NavigationController & Fragment with ViewController
Take a look at CarouselPage for Xamarin.Forms' own approach. It doesn't look like that's what you need but you can also look at its source code and maybe make a custom renderer yourself.
You may also want to take a look at MVVM
As for the easier/hackier way you'd want to make a button on each page and when the button is tapped execute Navigation.PushModalAsync(nextPage) - there won't be a "< Back" button any more, you may need to implement that yourself if you need it.
If by your meaning of 'current navigation stack' is for using the native Navigation of each platform, then remember that you don't have to use Xamarin.Forms' Navigation Model and functions such like PushAsync.
If you prefer to do Navigation with code specific to each platform then you can do this the same as normal. Just create your stub pages in each platform specific project and set the Xamarin.Forms content for each page from the shared project.
From each platform specific stub page (Activity / UIView / PhoneApplicationPage) you could then execute an Action<> call setting on the shared Xamarin.Forms page to help with the navigation, or alternatively, hook into a custom-event that is raised from the Xamarin.Forms** page back to the platform specific stub page to allow you to do navigation from there.
Like Sten mentioned there won't be any 'Back' button so you will most likely have to do that yourself.