I'm writing an Universal App in C# for Windows 10 using the SplitView with a frame for navigation.
I have a sidebar with a list that I load dynamically and, when I click on one of the items, I navigate to a page using the model from the menu to indicate which item I should load in the Frame.
I followed this sample: Windows-universal-samples/Samples/XamlNavigation/
The only difference is, instead of having multiple pages, I have only one page that is loaded every time I select a different item with its specific ViewModel. I use Autofac to load the ViewModels and MyFrame.Navigate(typeof(DetailsPage), idOfItem);to load the page.
The problem is, every time I navigate to the next page, it seems that the instance of the previous one is lost and when I navigate back, it loads a new instance. This kind of thing doesn't seem to happen when I'm navigating in the RootFrame and it didn't happen in Windows Phone 8.1.
I've been searching for a solution on the Web for hours, but I can't find anything relevant.
Does anyone know why this could be happening?
I hope I was clear enough with my question.
Thank you in advance for the answer.
The behavior you observe is correct and as expected. You have two options:
You can use Page.NavigationCacheMode, set it to Required. This is easy, but may consume a lot of memory.
Or you can save page state in OnNavigatedFrom and restore it in OnNavigatedTo. In fact, depending on your scenario, it may not even be necessary to save state in OnNavigatedFrom, assuming the state (your DataContext) can be constructed when returning to the page in the same way that you constructed it when first comming to the page.
Related
I've got a few issues with Xamarin.Communitytoolkit which doesn't load the video and then shows the page it waits for the page to appear to then actually load the video giving a very bad user experience with flicker loading and occasionally stutters or constant pause play effect.
I want to be able to load a page onto a stack way before the user actually clicks the next button which navigates to that page creating a new instance.
I saw this post on How to pre-load pages on SO but the problem is that this doesn't use shell so they don't have to deal with Routing. Also navigation is much different in Shell doing Shell.Current.GoToAsync(URI type navigation string?queries)
Is this possible to do with Shell? And if so how?
Update: After doing more research is that I need to insert a new page to the navigation stack before the user clicks next to then navigate to that page. This way the page will have everything ready for the user without loading anything again. This is actually happening while navigating backwards on the stack and there is nothing to do with the visual glitches which I see.
Many Thanks in advance.
public AppShell()
{
InitializeComponent();
Routing.RegisterRoute(nameof(ListenAndViewPage), typeof(ListenAndViewPage));
Routing.RegisterRoute(nameof(SpellPage), typeof(SpellPage));
Routing.RegisterRoute(nameof(CopyWhatIDoPage), typeof(CopyWhatIDoPage));
Routing.RegisterRoute(nameof(QuizPage), typeof(QuizPage));
}
Update-2:
I have a JSON file with Levels for my games and each level contains a Video path.
I have a Json reader which reads the file and then deserialize into my Level obj.
I then made a LevelReader which has methods to extract level data depending on CurrentLevel + other params if needed.
I load the MediaElement source with data binding from my ViewModel for the page.
The videos are part of iOS & Android projects as Android Resource or Bundle Resource.
I have an app where you could go through in views like;
play -> normal or custom -> select map -> summary -> start
I would like to make a shortcut option from play to summary, but I also want navigation back to select map page with the back button functionality.
So the normal workflow p->noc->sm->summary but I want to implement p->sm with the noc<-sm<-summary back functionality too (with the windows phone back button).
I saw how can I delete items from the backstack, but google not helped me how can I navigate through a couple of windows without showing that to the user.
Am I need to override the back button or there is a "better" way to do that?
It's a WP8 project.
Edit:
I didnt need the exact codesnippet for this just a design concept in this patform. (just for the is it duplicated guy)
My normal or custom and select map page should be randomized when I do the shortcut, both of these pages has a "button" which can randomize those settings, I just want a swipe->press->swipe->press->swipe actions shortened to a button press without loosing the 'post modification after randomized' feature.
After I read your comments I think I will handle the back button all of the mentioned views so the backstack will not be getting inconsistent at any state. If I understand well I can tell it in every page what is the "backed" page.
You can't inject pages into the backstack. You can override the back button and do a forward navigation with the animations you would normally do when going backward (and then remove the page you just came from off the stack), but honestly, this all gets complicated and for good reason. One of the few hard truths of Windows Phone design is that you shouldn't mess with the backstack.
Instead, I would rethink your flow. It seems like your second page is a setting of some sort (Normal or Custom). If that is changeable, maybe make a button that can float a modal popup on top of the page and move things around according to the new decision.
Looking again at your flow, it seems like several of the pages may be settings. Can you combine those into one page, maybe on a pivot or panorama? That way making changes is just a swipe away.
Regardless, while it is possible to do what you are looking to achieve, I would look long and hard at whether it is actually the best experience for your users.
I developed a quite popular news app for a newspaper. Unfortunately, my users reported the following problem that I can reproduce:
The App basically consists of a GroupedItemsPage and a ItemDetailPage (and several other pages, not important here). The GroupedItemsPage shows the news grouped by category. As the user scrolls to the right, he clicks on one of the items of interests, gets redirected to the ItemDetailPage and navigates back. Back on the GroupedItemsPage the view jumps back to the first group and does not stay at the last position (group) the user has been. The exact same behaviour can be found (in my environment) when I create a new Windows Store "Grid App".
Unfortunately, I was not able to resolve this problem on my own, nor have I found some useful comments in the web. I saw several other apps who could solve this issue and others didn't. Any comment would be very much appreciated. Thank you!
You need to implement this by your self. When navigating from GroupedItemsPage to ItemDetailPage you need to remember the click item. Then, when you navigate back to GroupedItemsPage you need to scroll to the remembered item. You can do it by using the ScrollIntoView method on your GridView.
I found another, easier solution. I'd like to share it:
In the GroupedItemsPage (XAML) i added:
<common:LayoutAwarePage
NavigationCacheMode="Enabled" ...
We have an application where we have a single level navigation menu with some heavy-duty pages on each link. The user can switch back and forth between these pages frequently to obtain information that he needs.
Once the page gets generated, it wouldn't change for the session. However, the page is specific to the user, hence we cant cache it.
I was trying to come up with a solution where we generate the page once, and keep it hidden in the background until its link is clicked, but haven't been able to get my head around this.
One of the ways I thought was to have multiple div tags (one for each page) on one page and keep toggling the visibility as the links are pressed, but that would end up making this single page very heavy. Someone also suggested using iFrames, but I am not really comfortable using the iFrames much and I'm not even sure, if it would be any helpful either.
Can you guys please suggest a few approaches to tackle the issue?
update: Just to clarify, we are fine with keeping the pages separate and navigate across using a standard menu bar. We were just looking for ways to optimize the performance as we know that the pages once generated wouldn't change and there should be some way to tap that benefit.
You can use Ajax tab control for this purpose
Try taking a look at this MSDN article which specifically tackles the issue of how to user-level cache. Also, it might be more manageable to break each tab into a user control. That way your ASP.NET page has just the tab control and 1 user control for each section under the tab. It makes managing tabs much easier.
EDIT:
What I would do in your case, since you say the data won't change for the user, is I would grab the static data from the database and then I would store that data in the Session cache. THe session cache is specific per user and you can try to retrieve the static data from there instead of repetitively calling the database.
Check out the ASP Multiview control. Just remember that even though the different views are hidden when not active, their viewstate is still being sent back and forth. Can be a benefit if you need to check control values across views though.
Is there any pattern or kind of "least requirements list" to follow for ensuring an asp.NET application to support BACK button of the browser for each aspx page?
thanks
In general, the back button on the browser will take you to the previous HTML GET or POST that occurred. It navigates by page-wide transactions, so anything done dynamically cannot be navigated that way. Also, the back button doesn't rewind code execution, so if you are determining something based off of a Session variable or something similar, that won't be rewound either. Obviously, it won't rewind database transactions either.
In general, if you want to support the back button, you'll need to make sure to divide everything you need to navigate between with said button is divided by an HTML transaction of some sort.
Again, you're going to run into issues if your page display is dependent on server-side control that changes from one post to the next. This is one reason you see some forms feed a 'Page has expired' error when you try to navigate back to them.
Not really... It depends on your application flow.
There are things that make supporting the back button more awkward.
for example using pure ajax to change the majority of the content on the page,
will look like a 'new' page but wont be compatible with the back button (though you can fudge it)
another example is posting back to the same page more than once, as this can make it appear like the back button is not working, and at the same time re-doing your request (and therefore database transactions)
Fundamentally it depends on your application requirements.