In Xamarin.Forms every ```View``` has the two properties ```HorizontalOptions``` and ```VerticalOptions```. Both are of type ```LayoutOptions``` and can have one of the following values:

&lt;!-- language: c# --&gt;

* ```LayoutOptions.Start```
* ```LayoutOptions.Center```
* ```LayoutOptions.End```
* ```LayoutOptions.Fill```
* ```LayoutOptions.StartAndExpand```
* ```LayoutOptions.CenterAndExpand```
* ```LayoutOptions.EndAndExpand```
* ```LayoutOptions.FillAndExpand```

Apparently it controls the view&#39;s alignment on the parent view. But how exactly is the behavior of each individual option? And what is the difference between ```Fill``` and the suffix ```Expand```?


What is the difference between Xamarin.Form&#39;s LayoutOptions, especially Fill and Expand?

I am confused between Xamarin.Forms and Xamarin native.

What is the difference between the two?

So what are the technical positives and negatives of using Xamarin.Forms over Xamarin Native?

What is the difference between Xamarin.Forms and Xamarin Native?

How do you switch between pages in Xamarin Forms?  

My main page is a ContentPage and I don&#39;t want to switch to something like a Tabbed Page.

I&#39;ve been able to pseudo-do it by finding parents of the controls that should trigger the new page until I find the ContentPage and then swap out the Content with controls for a new page. But this seems really sloppy.

How do you switch pages in Xamarin.Forms?

Is there any way using Xamarin Forms (not Android or iOS specific) to have a pop-up, like Android does with Toast, that needs no user interaction and goes away after a (short) period of time?  

From searching around all I&#39;m seeing are alerts that need user clicks to go away.

Toast equivalent for Xamarin Forms

I have the following method in an `Xamarin.Forms.ContentPage` wired to a button click event

&lt;!-- language: lang-cs --&gt;

    public class LoginPage : ContentPage
    {
        private Button _loginButton = null;
        private Entry _PasswordInput = null;
        private Entry _UsernameInput = null;
    
        public LoginPage()
        {
            _UsernameInput = new Entry { Placeholder = &quot;Username&quot; };
            _PasswordInput = new Entry { Placeholder = &quot;Password&quot;, IsPassword = true };
    
            _loginButton = new Button
            {
                Text = &quot;Login&quot;,
                BorderRadius = 5
            }
    
            _loginButton.Clicked += LogIn;
    
            Content = new StackLayout 
            {
                VerticalOptions = LayoutOptions.Center,
                Children = 
                {
                     _UsernameInput, _PasswordInput, _loginButton, 
                },
                Spacing = 15
            };
        }
    
        public async void LogIn(object sender, EventArgs eventsArgs)
        {
            //do authenticate stuff here
            SSO.MyAuthentication client = new SSO.MyAuthentication();
            
            bool isAuthenticated = client.Authenticate(_UsernameInput.Text, _PasswordInput.Text);
    
            if(isAuthenticated)
            {
                 //Push home page to top of navigation stack
                 Navigation.PushAsync(new HomePage());
            }
        }
    }

On the following line of code `Navigation.PushAsync(new HomePage());`, I am getting the following exception while debugging:

&gt; PushAsync is not supported globally on Android, please use a
&gt; NavigationPage

How do I resolve this issue using a `Xamarin.Forms.NavigationPage` object?

PushAsync is not supported globally on Android, please use a NavigationPage - Xamarin.Forms

Using *Xamarin.Forms*, how can I define the highlight/background color of a selected/tapped ListView item?

(My list has a black background and white text color, so the default highlight color on iOS is too bright. In contrast, on Android there is no highlighting at all - up to a subtle horizontal gray line.)

**Example:** (left: iOS, right: Android; while pressing &quot;Barn2&quot;)

&lt;img src=&quot;http://i.stack.imgur.com/2VSCB.png&quot; height=&quot;150&quot; /&gt;
&lt;img src=&quot;http://i.stack.imgur.com/r8xlt.png&quot; height=&quot;150&quot; /&gt;

Xamarin.Forms ListView: Set the highlight color of a tapped item

I&#39;m using Visual Studio to try out Xamarin.Forms. I&#39;m trying to follow the guide:
http://developer.xamarin.com/guides/cross-platform/xamarin-forms/xaml-for-xamarin-forms/getting_started_with_xaml/

In short, I create a Xamarin.Forms solution using a PCL and then try to add a `Forms XAML Page` to the PCL-project.

The code-behind that gets created looks like this:

&lt;!-- language: lang-cs --&gt;

        public partial class Page1 : ContentPage
        {
            public Page1()
            {
                InitializeComponent(); 
            }
        }

The problem here is that `InitializeComponent();` is red.
When I try to build I get informed that `The name &#39;InitializeComponent&#39; does not exist in the current context`	

I&#39;ve been looking around for solutions and even though others have had the same trouble, their solutions wont work for me. Here is one suggestion i tried to use:
http://blog.falafel.com/xamarin-error-initializecomponent-does-not-exist-in-the-current-context/

Please let me know if you have a solution for this problem. Thanks!

Update:

My PCL (which is where I also want to add my XAML-page) contains:

App.cs:

&lt;!-- language: lang-cs --&gt;

        public class App : Application
        {
            public App()
            {
                // The root page of your application
                MainPage = new ContentPage
                {
                    Content = new StackLayout
                    {
                        VerticalOptions = LayoutOptions.Center,
                        Children = {
    						new Label {
    							XAlign = TextAlignment.Center,
    							Text = &quot;Welcome to Xamarin Forms!&quot;
    						}
    					}
                    }
                };
            }
    
            protected override void OnStart()
            {
                // Handle when your app starts
            }
    
            protected override void OnSleep()
            {
                // Handle when your app sleeps
            }
    
            protected override void OnResume()
            {
                // Handle when your app resumes
            }
        }

And my XAML-page:

&lt;!-- language: lang-xml --&gt;

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot; ?&gt;
    &lt;ContentPage xmlns=&quot;http://xamarin.com/schemas/2014/forms&quot;
                 xmlns:x=&quot;http://schemas.microsoft.com/winfx/2009/xaml&quot;
                 x:Class=&quot;XamaTest.MyXamlPage&quot;&gt;
    	&lt;Label Text=&quot;{Binding MainText}&quot; VerticalOptions=&quot;Center&quot; HorizontalOptions=&quot;Center&quot; /&gt;
    &lt;/ContentPage&gt;

Code-behind:

 &lt;!-- language: lang-cs --&gt;

        public partial class MyXamlPage : ContentPage
        {
            public MyXamlPage()
            {
                InitializeComponent();
            }
        }

Xamarin.Forms - InitializeComponent doesn&#39;t exist when creating a new page

I&#39;m rewriting my existing (swift) iOS physical therapy app &quot;On My Nerves&quot; to Xamarin.Forms. It&#39;s a timer app to help people with nerve damage (like me!) do their desensitization exercises. You have these &quot;fabrics&quot; (e.g. a feather) where each fabric has an &#39;x&#39; second countdown. When once fabric&#39;s timer reaches 0, a message box appears saying &quot;time&#39;s up&quot;. The user hits OK and the next fabric starts its countdown. Rinse and repeat for all fabrics in the list. Here&#39;s a [video showing the workflow][1]. Trust me on the UX in the video. 

Here&#39;s my [sample app code demonstrating this behavior][2]. 

The `DoSomethingForNow` method (forgive my naming strategy) is the callback from the NotificationService (see line 65 - not enough SO rep points for direct link) that is created when the timer starts, in case the app gets the background.

The specific call that is not working on Release mode on Device is at line 115 

    Device.BeginInvokeOnMainThread(
                    async () =&gt; await ShowAlertAndWaitForUser(currentFabricCount));


The `async () =&gt; await ShowAlertAndWaitForUser(currentFabricCount))` works as expected in Debug and Release configuration on iOS Simulator, and in Debug configuration on the device. 

However, the message box indicating time is up **does not appear in Release config on the physical device**. I cannot figure out why `Device.BeginInvokeOnMainThread()` doesn&#39;t work in Release config on device. What is going on?  

*Side note re using* ***`Device.StartTimer()`***

*The reason why I switched from* *`Device.StartTimer()`* *to James&#39;s FrenchPressTimer solution (see jamesmontemagno/FrenchPressTimer) early on is because I need a way to cancel / stop / whatever a* *`Device.StartTimer()`* *in case the user needs to pause or stop the countdown on the app.*

*The* *`Device.StartTimer()`* *code works great for me on all configurations on both simulator and device and thankfully someone showed me how to cancel a Device.StartTimer (thanks!). If you want to see this working solution, check out saraford/Device-StartTimer-Working-Xamarin on GitHub.*
 
My specific question is why doesn&#39;t `Device.BeginInvokeOnMainThread()` display a message box when invoked from a notification callback in Release config on a physical device.

I&#39;ve also tried the different linker combinations. No effect. 

  [1]: https://1drv.ms/v/s!Ard2PoaGcK2ig44w8h51K_Bx4T4Dyw
  [2]: https://github.com/saraford/Xamarin-Timer-Threading-Issue/blob/master/App1/App1/MainPage.xaml.cs

In Xamarin.Forms Device.BeginInvokeOnMainThread() doesn’t show message box from notification callback *only* in Release config on physical device

I have a simple Xamarin Forms app. I&#39;ve now got a simple POCO object (eg. `User` instance or an list of the most recent tweets or orders or whatever).

How can I store this object locally to the device? Lets imagine I serialize it as JSON.

Also, how secure is this data? Is it part of Keychains, etc? Auto backed up? 

cheers!

How can I save some user data locally on my Xamarin Forms app?

I am developing an app using Xamarin Forms PCL. I need a StackLayout with rounded corners. I have tried frame as well for rounded corner container but there is no corner radius property available for it. I cannot find renderers for iOS,Android,UWP,Windows 8.1.

Please can any one suggest me how to achieve StackLayout with rounded corners along with corner radius property for all the platforms.
[![enter image description here][1]][1] 

  [1]: https://i.stack.imgur.com/eGT8N.png

Xamarin Forms: StackLayout with rounded corners

I am using a third party library ([Splunk c# SDK][1] ) in my ASP.NET core application.  I am trying to connect to my localhost Splunk service via this SDK, but I get an exception saying: 

&gt; System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.

And The inner exception says:

&gt; The remote certificate is invalid according to the validation procedure.

This SDK uses HTTP client under the hood, but I don&#39;t have access to this object to configure HttpClientHandler.  

All my search on google ends up using ServicePointManager to bypass the SSL validation, but this solution doesn&#39;t work in Asp.Net core. 

    ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

Is there any way to bypass this validation in asp.Net core?

  [1]: http://dev.splunk.com/csharp

The SSL connection could not be established

I am new to Xamarin platform, and am facing the error 

`Build action &#39;EmbeddedResource&#39; is not supported by one or more of the project&#39;s targets.` Am debugging in `emulator 8.1 for windows phone`, and my project is a `Xamarin.form(portable)`.



Build action &#39;EmbeddedResource&#39; is not supported by one or more of the project&#39;s targets

I replaced all the images everywhere (by this I mean in drawable folders and all Windows Assets folders and iOS Resources folder), but it still shows me the default Xamarin icon for the app. I tried this code, too, but it doesn&#39;t seem to work either. Can someone tell me the solution?

    [assembly: Application(Icon = &quot;@drawable/icon&quot;)]



How to change application icon in Xamarin.Forms?

I have an app using Xamarin.Forms targeting IOS, Android and WP 8. 

I need push notification feature in my app. 

I have seen the `pushsharp` demos and it seems promising. But all the codes I have seen are done separately for each platform. 

I would like it to be done in the Xamarin.Forms project, somewhere in the App.cs so that I don&#39;t need to repeat the code for registering device, and handle how push notifications should be processed. 

Any help would be greatly appreciated. Sample codes or tutorial references are welcome. 

**Edit** : I implemented it based on Idot&#39;s [answer][1]. Here is the **[link][2]** for my answer. 


  [1]: https://stackoverflow.com/a/29141884/1155650
  [2]: https://stackoverflow.com/a/29126946/1155650

How to use Push Notifications in Xamarin Forms

I&#39;m making an application in Xamarin forms but I have some trouble sticking a layout to the bottom of the device. I thought an AbsoluteLayout would work, but I cannot grasp how it works. So I made a RelativeLayout which I filled with the elements I wanted to fill but now I cannot seem to get it working on sticking to the bottom of the device at all time. 

Below is a screenshot to make things hopefully a little bit more clear.
I have a stacklayout which I fill with the headerlayout and the contentlayout. But if I just add the footerlayout to the stacklayout, it will not be sticked to the bottom of the page but (logically) just behind the previous child. Now I think an Absolutelayout would do the trick, but I cannot seem to grasp the functionality and the Layoutflags and bounds of it. Could someone help me out?

![My application][1]


  [1]: http://i.stack.imgur.com/Tzgqz.png

Stick Layout in Xamarin Forms to bottom

I&#39;d like to use **horizontal separator** lines in a form. As far as I found out, Xamarin.Forms doesn&#39;t provide one.

Could someone provide a snippet for separators?

**UPDATE 1**

According to Jason&#39;s proposal, this looks fine:

&lt;!-- language: lang-cs --&gt;

    // draws a separator line and space of 5 above and below the separator    
    new BoxView() { Color = Color.White, HeightRequest = 5  },
    new BoxView() { Color = Color.Gray, HeightRequest = 1, Opacity = 0.5  },
    new BoxView() { Color = Color.White, HeightRequest = 5  },

Renders the below separator line:

![enter image description here][1]


  [1]: http://i.stack.imgur.com/E4ZCD.jpg


Separators in Xamarin.Forms

Is there a way to create a vertical stack layout with a button that takes 30% of of the parent, and a text input that takes 70% of the parent? Something like this:


&lt;!-- language: lang-xml --&gt;

    &lt;StackLayout Orientation=&quot;Vertical&quot;&gt;
    	&lt;Entry Height=&quot;70%&quot;&gt;&lt;/Entry&gt;
    	&lt;Button Height=&quot;30%&quot;&gt;Click me&lt;/Button&gt;
    &lt;/StackLayout&gt;

But this doesn&#39;t work. Only solution so far is creating a complete Grid item and using that. Are there no other solutions?

Xamarin Forms StackLayout: How to set width / height of children to percentages

I&#39;m working on a Xamarin Forms project.  I want to target Android and Windows 10 UWP.  

When I try to clean up the PCL by removing &quot;Windows 8&quot;, &quot;Windows Phone Silverlight 8&quot;, &quot;Windows Phone 8.1&quot;, &quot;Xamarin.ios&quot;, and &quot;Xamarin.ios (classic)&quot; from the PCL targets, I get the following nasty...

I&#39;m really just trying to remove WP8 as I don&#39;t care about targeting it.

&gt; The project&#39;s targets cannot be changed.  The selected targets require
&gt; the project to opt-into NuGet 3.0 support, however, Visual Studio
&gt; cannot automatically do this for you.  Please uninstall all NuGet
&gt; packages and try again.

How do you get a project to opt-into NuGet 3.0? 
Something else I should try?

environ: Xamarin Forms, VS2015

[![enter image description here][1]][1]

Thanks....


  [1]: http://i.stack.imgur.com/wBfST.png

Remove ios, windows8, and wp8 from Xamarin Forms PCL - nuget 3.0 opt-into error?

I have a set up XAML code below.

    &lt;Label Text=&quot;{Binding Date}&quot;&gt;&lt;/Label&gt;
    &lt;Label Text=&quot;{Binding Time}&#39;}&quot;&gt;&lt;/Label&gt;

I want result like september 12,2014 2:30 PM.




All xamarin.forms Solutions on Gang of Coders

Total of 19 xamarin.forms Solutions

What is the difference between Xamarin.Form's LayoutOptions, especially Fill and Expand?