xamarin

Xamarin.Forms: Lazy loaded Command snippet for Visual Studio

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Use xamcomm tab tab to generate commands in ViewModels with this snippet

IntelliSense recommendation

Snippet in work

Save the snippet file as {name}.snippet in Visual Studio’s folder: C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC#\Snippets\1033\Visual C#

<?xml version="1.0" encoding="utf-8" ?>
<CodeSnippets  xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
	<CodeSnippet Format="1.0.0">
		<Header>
			<Title>Xamarin Lazy Command</Title>
			<Shortcut>xamcomm</Shortcut>
			<Description>Xamarin Command declaration code snippet for MVVM design pattern</Description>
			<Author>banditoth.hu</Author>
			<SnippetTypes>
				<SnippetType>Expansion</SnippetType>
			</SnippetTypes>
		</Header>
		<Snippet>
			<Declarations>
				<Literal>
					<ID>BackFieldName</ID>
					<ToolTip>Backfield Name</ToolTip>
					<Default>_backfieldname</Default>
				</Literal>
				<Literal>
					<ID>CommandName</ID>
					<ToolTip>Command name</ToolTip>
					<Default>CommandName</Default>
				</Literal>
				<Literal>
					<ID>ActionToExecute</ID>
					<ToolTip>Action to execute</ToolTip>
					<Default>() => { return; /*TODO: Implement logic for this Command*/ }</Default>
				</Literal>
        <Literal>
          <ID>ActionCanExecute</ID>
          <ToolTip>Action to determine can execute</ToolTip>
          <Default>() => true</Default>
        </Literal>
			</Declarations>
			<Code Language="csharp">
			<![CDATA[
	private Command $BackFieldName$Command;

	public Command $CommandName$Command
	{
		get { return $BackFieldName$Command ?? ($BackFieldName$Command = new Command($ActionToExecute$,$ActionCanExecute$)); }
	}
	$end$]]>
			</Code>
		</Snippet>
	</CodeSnippet>
</CodeSnippets>
This content has 3 years. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

Xamarin.Forms: Bypass SSL Certificate validation on Android

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Disclaimer: Bypassing SSL Certificate validation in production releases are not recommended. It can make your application vulnerable by hackers and reverse engineers, and your users will be unprotected from the bad guys. Consider to use the following codes with compile directives.

But in the other hand, it can be handful to just ignore the certification errors in development enviroment. Local machines has self signed certificates, and it is easier to just bypass the validation method, rather than set the self signed certificate acceptance in our client applications.

In Xamarin.Android (Lower than Android 10) and Xamarin.iOS, use the ServicePointManager in order to make your own certificate validator algorithm. The code below just accepts every cert.

ServicePointManager.ServerCertificateValidationCallback =
            (message, certificate, chain, sslPolicyErrors) => true;

To bring Android 10 also to work, construct your HttpClient with the following constructor:

            var httpClientHandler = new HttpClientHandler();
#if DEBUG
            httpClientHandler.ServerCertificateCustomValidationCallback =
                (message, certificate, chain, sslPolicyErrors) => true;
#endif
            var httpClient= new HttpClient(httpClientHandler);
This content has 3 years. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

[Xamarin.Android]: Cleartext HTTP traffic to not permitted

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If your Android application gives the following error, when trying to use a HttpClient:

Java.IO.IOException: 'Cleartext HTTP traffic to 192.168.0.10 not permitted'

Set usesClearTraffic property to true in the AndroidManifest.xml:

<application android:label="MobileSolution.Android" 
	     android:theme="@style/MainTheme"
             android:usesCleartextTraffic="true">
		
</application>

The restriction was introduced in Android 8. More explanation: https://koz.io/android-m-and-the-war-on-cleartext-traffic/

This content has 3 years. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

Xamarin.Forms : Using styles on custom UserControls

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To use styles for your custom usercontrol, you have to define the styles TargetType property with an x:Type in your resource dictionary.

<ResourceDictionary
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:buttons="clr-namespace:AnAwesomeApp.Controls.Buttons"
    x:Class="AnAwesomeApp.Resources.Styles">

Declare the clr-namespace where your custom usercontrol lives.

<Style
        x:Key="BlueButtonStyle"
        TargetType="{x:Type buttons:ColoredButton}">
        <Setter
            Property="TextColor"
            Value="White" />
        <Setter
            Property="Color"
            Value="{AppThemeBinding Dark=#2325A6, Light=#61BAFF}" />
        <Setter
            Property="FontFamily"
            Value="Nunito" />
    </Style>

Set the target type with x:Type.

And boom, done!

This content has 3 years. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

[Xamarin.Forms] Custom font handling made easy by MS

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No more sorrow with custom font defining in Xamarin.Forms. Later we had to define a ResourceDictionary for storing platform specific filenames for our ttf files, import for each platform specific project the ttf file, and set a specific build action for them.

Now we only need to import the TTF file to our Xamarin.Forms project, and set the build action to BundleResource, and add a new line to assembly.cs:

[assembly: ExportFont("Nunito-Light.ttf", Alias = "Nunito")]

See reference at: https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/text/fonts

Appreciate it!

This content has 3 years. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.