I'm just learning about how to navigate between pages and tombstoning. I'm wondering if anyone can point me to some good examples that not only show me the basics of how to use Navigation properly but also good examples of more complicated and advanced navigation issues?
Some questions I have revolve around memory leaks when navigating to other pages and navigating back?
Is there a close page call, once the page has done its job (I don't want an instance of it hanging around after I'm done with it)?
Another question is how to I maintain state if the app gets tombstoned (still trying to wrap my head around that term).
Thanks!
There's no close page call, the OS automatically closes pages when they're backed out and releases used memory (so there should be no leaks here).
Some resources here that cover tombstoning and advanced navigation concepts.
Understanding the Windows Phone Application Execution Model, Tombstoning, Launcher and Choosers, and Few More Things That Are on the Way – Part 1, Part 2, Part 3
Introducing the concept of “Places” - Peter Torr's Blog
Redirecting an initial navigation - Peter Torr's Blog
I like thinking about WP7 navigation like a simple browser that only have back button. The Naviation model is based on stack pattern (Last In First Out), need to get through all to get back to first page. This is not what PC user are used to but in mobile world is one of the best solution.
You have to stick to this model and never ever do "go to home page" button - your app will not pass the certification for sure(there are some workaround with excetions but I wouldnt recommend that).
A lot of pages can get the user pissed that's why a good idea is to have 3 to 5 pages max. For instance, first page user picks what he is going to do, next page is login page and then for more complex interface use panorama and pivot control.
To the simple browser model add cookies. When your browser load a page it sets a cookie with some information, next you close the browser and when you go back to the page it can get the previous state from that cookie. Tombstoning is very simailar. - link. Some more info about tombstoning
Some questions I have revolve around memory leaks when navigating to other pages and navigating back?
What do you mean by memory leaks? you are working in managed framework.
Is there a close page call, once the page has done its job (I don't want an instance of it hanging around after I'm done with it)?
you do not have to do this. Page is destroyed everytime you go to the next page unless a thread is still working there.
Another question is how to I maintain state if the app gets tombstoned (still trying to wrap my head around that term).
Basically it's up to develepor to manage this. It is not mandatory but gives a nice user experience.
Another question is how to I maintain state if the app gets tombstoned (still trying to wrap my head around that term).
Use Isolated Storage.
You can have a look into Columbus MVC framework for WP7 source code (http://columbus.codeplex.com/) that I have published recently. Columbus addresses both Navigation and Tombstoning (provides strongly typed navigation with history and View Models that can survive tombstoning).
Related
Now this has come up a fair bit on here so I guess I'm looking for an explanation rather than a fix (though that would be ace), but Safari's back / forwards cache is horrifically greedy.
I've got an issue where a form submits, but loads an interstitial modal window before moving on to the form action page. On Safari the cache is so strong that the back button has the modal open still which is making my soul very sad.
I'm hacking around it by dismissing the modal and then submitting the form. On back the browser has a half closed modal (it's Bootstrap so it fades) which then just carries on dismissing.
Now I know about onunload="" but refreshing the page just seems crazy. The cache is a good thing and something you want, specially on mobiles.
I guess my question is:
Why is it so much more intense than say Chrome and is there anyway of forcing the browser to cache a state instead of just the last state?
Thanks
Hah, greedy is an understatement! Honestly though, 99% of the time, the caching design behind Safari is the ideal way to handle page transitions on a mobile device.
When you go from Page A to Page B, and then back to Page A, you don't want to burden the device (bandwidth, battery life) with fetching resources and assets, when you could just "paused" the state between interactions, and then "continue" it when you navigate back.
That's effectively what Safari Mobile does. They use a concept of Page Cache, which keeps the entire page live in memory, when you navigate from one to another. This reduces the need to fetch those resources, and allows for a snappy interaction when clicking back.
That's great and all...but it does lead to problems (such as the one you brought up) - Specifically, how do you distinguish between a page that was suspended and one that should have been destroyed?
Thankfully, WebKit provides a pageshow and pagehide event that tap into Page Cache. In addition to firing when the page shows or hides (similar to onunload), it has the nifty ability to indicate whether a page was persisted - or placed into the Page Cache.
While it's not a perfect solution, you could check the pageshow event for persistence, and then handle the modal more directly (since you know it was cached) like immediately hiding it.
If you haven't already, take a look at these two links here:
https://www.webkit.org/blog/427/webkit-page-cache-i-the-basics/
https://www.webkit.org/blog/516/webkit-page-cache-ii-the-unload-event/
They do a great job explaining the Page Cache and include code samples of the pageshow and pagehide event I referenced earlier.
Hope this helps!
I have the application ,in which i save the state of the page and while deactivate the application,and once i get in foreground the application,i will restore the data.But when i click the back button at the time,i don't have the Object instance for the previous page .So how can i handle at that time?
On BackKey Press,I need to some thing like
1)Check the pages in the stack,remove the previous page and create the new instance of the page or any other think?
Your data should be saved when your application is deactivated and reloaded when your application is restored. It sounds like you are not restoring your data correctly.
This is where using something like MVVM model where your data is separate from your UI code is really helpful. Check out the MVVM light toolkit on CodePlex.
http://mvvmlight.codeplex.com/
It is too general a question to give more specific answers than that. Sorry.
Try coding up something and posting specific questions regarding your code.
I'm creating an app that has start button which brings you to start page from anywhere in app.
However back navigation stack hurts when I just navigate to start page.
Looking for solution I found NonLinearNavigationService. The trouble is that download links are target to app hub, which (now, as we have new better app hub) redirects me to main page and nowhere further. Also I failed to find it on app hub using build in search engine.
Anyone knows where from can I get it?
Or maybe another solution for navigation loops?
If you use RemoveBackEntry(), the entries are programmatically cleared from the backstack so you don't have to deal with the side effects of actually navigating back through the pages to pop them off the stack.
The NonLinear Navigation Service effectively does what you have tried. It calls GoBack() to traverse back up the stack. What it additionally does to prevent the flicker is to make the root frame transparent. See this question:
Skip a page when the back button is pressed, WP7
I don't want to call your question a duplicate because I think before Mango came out, that was probably the solution that needed to be used. Now that RemoveBackEntry() has been added to NavigationService, I think using that would probably be the better approach.
No linear navigation in WP7 is generally not recommended, because of the hardware back button and the UX on the rest of the phone, so you should probably structure your app to avoid this. However it should pass the certification process.
Here's another similar question In-App Home Button to Navigate to MainPage allowed? and an article about circular navigation which mentions the NonLinearNavigationService you are talking about http://windowsteamblog.com/windows_phone/b/wpdev/archive/2010/12/13/solving-circular-navigation-in-windows-phone-silverlight-applications.aspx.
If the only non-linear part of the navigation is the home button, you could use NavigationService.RemoveBackEntry() in a loop untill it raises an InvalidOperationException in the home button event. When the InvalidOperationException is raised the BackStack is empty and the next click on the back button exits the application.
I am new to windows phone (WP7) and to me it looks like everything on WP7 is about pages. I want a small window to pop up from the bottom of a page while staying on the same page. The small window will have some controls (like slider, list etc.). It should not behave like a modal dialog box though, i.e. the rest of the page (which is not covered by the small window) should still be active and user should be able to do something there. And I want to have a separate C# class which will handle the events from the controls on the small window.
This is very easy on iPhone, using view controllers, is there something similar on windows phone?
It sounds that it would make sense to make your "pop up" part of the page with the content it is intended to manipulate content on that page. If you want to encapsulate the functionality of the "pop up" you could make it a UserControl. If you went this route then animating it to slide onto the screen will be straightforward.
Windows Phone 7 typically uses an MVVM model compared to iPhone's MVC one for app structure. The direct comparison therefore isn't appropriate. WP7 also uses a very different design language to that of the iPhone and so a straight port of application design and layout is also unlikely to create a great experience on WP7.
I'd recommend taking some time to understanding the differences in the platforms and how your existing design would be best suited to recreation on WP7. Not only will this help you create a better experience on WP7 but enable to see if this your question actually relates to something you should be doing or not.
This very much sounds like something that goes against the nature of the platform, and the general design guidelines.
If you're providing some available configuration options to the user, you should do it on a separate page, so the user can change the settings there, approve it, and then be navigated back to the previous page.
However, if you really want to, you're talking about displaying a UserControl inside a Popup. But it wouldn't be a very good user experience, and confuse most users, as it doesn't follow the same look&feel as the rest of the platform.
I have spent a bit of time rummaging through Stack Overflow to find out how to deterministically close an application based on an action. Most if not all answers say you can't or shouldn't do it. If this is so I would like to phrase my question differently and see how people are handling two issues I am having trouble with.
Just to let you guys know I am using Caliburn.Micro for this project.
Ok so the flow of my app can be broken down into two parts, the initial flow and the standard flow, these are as follows
Splash -> Welcome -> CreateAccount -> MainHub (all other functionality branches from here)
Splash -> MainHub (all other functionality branches from here)
Based on this flow, the feedback from my better (beta) testers is that they expect to exit the app on pressing the back button on the hub, which they see as the entry point. Currently as per navigation they go all the way back to the splash.
I see other apps have this functionality, but without forcing the application to close (Which I read is a no no) how are they achieving this desired functionality.
NOTE: I do not want to put in an exit button as I believe it goes against the natural flow of a WP7 application.
First of all, you cannot add a exit button. The only way to exit a application is to crash it, which will not be approved for marketplace certification.
As for your problem, you simply have to remove views from the navigation stack upon completion of a known navigation.
For this, use NavigationService.RemoveBackEntry.
You can access the NavigationService from anywhere, using this snippet:
(App.Current.RootVisual as PhoneApplicationFrame).RemoveBackEntry()
Regarding EULA / Login screens (and Splash) - don't make them into pages. If you instead make them Popup or Dialog controls you can show or hide them at any time (on first navigation; when the user hits a "protected" part of the app; after a time-out; etc.) and they don't consume a slot in the backstack.
Source: http://blogs.msdn.com/b/ptorr/archive/2010/08/01/exiting-a-windows-phone-application.aspx