Thursday, 30 July 2015

Page.Loaded Fails to Fire

Yesterday, we installed windows 10.

We tried out our app BouncingBalls and was surprised that the balls didn’t start bouncing, when they did on Windows 8.1

Even more oddly, if you opened the settings page, they would suddenly start bouncing.

Firing up the debugger, we found that Page.Loaded was not firing when we navigated to the main page.  The code we use is similar across all of our apps, but for some reason this particular app was not behaving.

After quite a bit of code hacking, we found it came down to the handling of the splash screen.

We add a handler for Splashscreen.Dismissed, and handle navigation to the main page (or another page depending on trial mode) from there.

In our OnLaunched handler, we called

Window.Current.Content = _launchframe;

but we hadn’t yet navigated to a page, or set any content for our frame _launchframe.

In the Dismissed handler, we did this:

var nowarn = _launchFrame.Dispatcher.RunAsync( CoreDispatcherPriority.Normal, () => ContinueAfterSplash1());

And in ContinueAfterSplash1() we eventually call after a few async calls.

_launchFrame.Navigate(typeof(BouncingBalls.MainPage), args)

MainPage received an OnNavigatedTo call, but never received the Loaded event we wired up.

The solution?

In the end, we changed the code not to call Window.Current.Content until after we successfully navigated to the MainPage.

For whatever reason, that caused the Loaded event to fire every time.

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