Develop Reference

How can I provide quick exit from WebView that has back history traversal?

Several SO questions cover the topic of how to wire up a WebView to have the "back" button traverse browser history. An Android developer doc page answers that question well. We have an app that uses the recommended method:
#Override
public void onBackPressed() {
if (mWebView.canGoBack()) {
mWebView.goBack();
return;
}
// Otherwise defer to system default behavior.
super.onBackPressed();
}
And that works fine. But the doc page also cautions,
Be careful when using this mechanism with highly dynamic web pages
that can grow a large history. Pages that generate an extensive
history, such as those that make frequent changes to the document
hash, may make it tedious for users to get out of your activity.
Our client has confirmed that this is a problem: When following over a dozen successive links within a WebView, getting back out to the previous (parent) activity is tedious, especially because you have to wait between taps of the back button for the WebView to refresh.
Unfortunately the developer doc page doesn't suggest a workaround for this situation.
One possibility is to use the "up" button in the toolbar/appBar/actionBar to exit the WebView.
My concern with that is that the "up" button normally looks like a backward-pointing arrow or chevron, very similar to the "back" button (identical to the "back" arrow in some browsers). So then we'd have an "up" button in the toolbar and the Android "back" button, looking very similar and doing something different. That would seem confusing to the user.
Is there a better way to provide "exit" navigation from a WebView besides the "back" button?
(Not a duplicate: using phones back button to exit from webview asks how to get the "back" button to exit the WebView only after there's no more history to traverse back over.)

One possibility is to use the "up" button in the toolbar/appBar/actionBar to exit the WebView.
What else would you have in the toolbar? What would it do?
Usually every screen that is not the root has a home (up) button in the toolbar that closes the screen again. That's how most Android apps work.
My concern with that is that the "up" button normally looks like a backward-pointing arrow or chevron, very similar in concept to the "back" button (identical to the "back" arrow in some browsers). So then we'd have an "up" button in the toolbar and the Android "back" button, looking very similar and doing something different. Is that a recipe for confusing the user?
That's Android and if you do it that way you follow the platform guidelines. As mentioned above, that arrow in the toolbar is in almost every app and navigates away from the current screen, whether its called home, back, up, or something else.
But you're right, back and up gets confused a lot.
An alternative is to opt for the close style. Replace the default arrow by an ✖ and its action closes the current screen should be evident.
While I prefer the Up arrow, the ✖ is a valid alternative, especially if you pop some WebView for additional content and want a strong indicator on how to close it again.
Is there a better way to provide "exit" navigation from a WebView besides the "back" button?
Nope. You could try asking on UX Stack Exchange, but you already have 2 platform standards—namely back and up—that can and should be used for navigation.
Anything else that you might come up with would be "new" and unique to your app, but of course you could just add a "Close Screen" button.
tl;dr If you don't like the Up Arrow in your toolbar use an ✖ as a close icon.

Prism Navigation in Xamarin Forms - MasterDetailPage

I have a master detail page setup using Prism 6.3 pre-2, I've finally got it working as I expected for navigating to "detail" pages; so the hamburger button shows the slide drawer and I have a simple ListView bound to the ViewModel, I list some items, and I use the NavigateCommand to navigate correctly.
Now, the expected behaviour (in Android), is when you've navigated to other items in the slide-out menu, you should be able to use the hardware back button to navigate back to the very first "detail" page shown.
For example, say your app has this setup, and the items listed are Inbox, Drafts, and Sent. The default view is going to be whatever you decide is the default detail view, in this example, it will most likely be Inbox. So if I navigate to Sent, and then press back, it should go back to Inbox, also, if I go to Sent -> Drafts, and then press back, it should go back to Inbox, as this is the default starting point, if you then press back again, the app should exit. At the moment, using Prism navigation, no matter what page you navigate to using this setup, it will exit straight away.
Please note, I have set it up correctly, I essentially have something like this (as an exmaple):
await NavigationService.NavigateAsync("RootPage/BaseNavigationPage/InboxPage");
When I navigate to say another page like Sent, the relative URI is like so:
"BaseNavigationPage/SentPage"
Now, when back is pressed, it should go back to the InboxPage, I'm not sure how this can be fixed... Brain...???
In addition to this, there is one other unexpected behaviour that is missing.
If I want to show a modal page whilst using a Master Detail Page, it doesn't work as any app written by Google does... This is easy to see if you open any google app that has this layout. If you show a modal window for say Settings, it pops up, has the navigation title set and a back arrow, basically looks exactly the same as if you've navigated one step further down like:
"RootPage/BaseNavigationPage/InboxPage/EmailPage"
However, I expected this functionality to be available if I did the following:
"BaseNavigationPage/SettingsPage", useModalNavigation:true
If you simply play around with any Google made application you'll see these features, and these are what I expect and they feel natural.
Any help available to achieve this...? again...Brian...?
All of this should be simple, but it's proving not to be...

To get the behavior you are wanting with the NavigationPage in a MasterDetailPage scenario, you must create a custom NavigationPage that implements INavigationPageOptions and set the ClearNavigationStackOnNavigation property to false. This will kep the NavigationPage's navigation stack in place with each navigation operation.
As to your other "expected behavior" regarding modal navigation, your understandings about modal navigation are wrong. Modal navigation does not provide a software back button. Any time you want a software back button you must have the pages wrapped in a NavigationPage,

Android Navigation Drawer proper handling activities

When you enter my app, you always go to the main screen with some quick details/information. There is a navigation drawer which contains 3 items: Recordings, Videos, Settings. I would prefer navigation work where Recordings and Videos are the top activity actions, so if you navigate down either and press Up/Home or Back button, you would ultimately navigate back up to the Main Screen. So if you switch from Recordings to Videos, and press back, you should go back to Main and vice a verse. Main should always be the ultimate top activity.
If you hit Settings, you should go back to where ever you previously came from (i.e. if on videos, go back to videos, if on recordings go back to recordings or if on main, go back to main). Settings is cross-cutting and should always take you back to where you previously were.
How do I best implement this with the Navigation Drawer? I believe it will be something with clearing the stack once you enter either Recordings or Videos, but I am unsure what it is I need to search for to find this.

The fix was to override onBackPressed to navigate back to the main screen, so long as the appropriate launchMode is set in either the Android Manifest or Intent flags.
Thanks #cricket_007

Up button for low level activities works automatically, why? (setDisplayHomeAsUpEnabled)

I am working through Android programming tutorials and am trying to learn "Up" navigation. I got it to work by adding setDisplayHomeAsUpEnabled, but when I remove this statement, clean the project and re-deploy, up navigation still works. Why does this happen? I should just see a static, go-nowhere child activity screen, shouldn't I?

Activities are automatically pushed onto a stack, the up/back button naturally pops the stack.
Life cycle of Android Activity after pressing Back button

Navigation Drawer "Up" button when in deeper sections

I want to transform the upper left button that normally allows to open the Navigation Drawer to become a "Up" button (with the left arrow).
I looked everywhere but I couldn't find even a question where this problem is answered in a quick way.
Details:
I have a single Activity. The NavigationDrawer contains a list of elements. Let's call them Element1 and so on.
When I open the application I can see a "Home" Fragment that contains a sort of splash screen with some basic details of my application.
If I open the Drawer and select Element4 I switch the "Home" Fragment with the "Element4" Fragment. The icon at the top left should become the classic "Up" icon as intended in the Google developer site and allow me, touching it, to come back to the "Home" Fragment.
A simple example could be the NavigationDrawer application mockup created by Eclipse in its wizard. I want to modify it to make the 0 section the home section and if the 1 section its child.
Maybe if someone that knows how to do answer me it'll be a big help not only for me but for many other people.
Thanks