I am new to MvvmCross 6.0 and Xamarin.
I am trying to follow the tutorial here that for MvvmCrosss 5.5
I followed the explanation,
Created App.xaml as MvxFormsApplication
<?xml version="1.0" encoding="utf-8" ?>
<core:MvxFormsApplication xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:core="clr-namespace:MvvmCross.Forms.Core;assembly=MvvmCross.Forms"
x:Class="App3.App">
</core:MvxFormsApplication>
CoreApp.cs as MvxApplication and runs RegisterAppStart(); in my overrided Initialize()
public class CoreApp : MvxApplication
{
public override void Initialize()
{
CreatableTypes()
.EndingWith("Service")
.AsInterfaces()
.RegisterAsLazySingleton();
CreatableTypes()
.EndingWith("Client")
.AsInterfaces()
.RegisterAsLazySingleton();
// register the appstart object
RegisterAppStart<MainPageViewModel>();
}
}
MainPageViewModel to inherited MvxViewModel
public class MainPageViewModel : MvxViewModel
{
}
View that created as MvxContentPage with type MainPageViewModel
<Label Text="Welcome to Xamarin.Forms!"
VerticalOptions="Center"
HorizontalOptions="Center" />
Removed MainActivity and created a file called MainApplication.cs as follow
[Activity(Label = "MvvmcrossGettingStarted", Icon = "#drawable/icon", Theme = "#style/MainTheme", MainLauncher = true,
ConfigurationChanges = ConfigChanges.ScreenSize |
ConfigChanges.Orientation)]
public class MainActivity : MvxFormsAppCompatActivity
{
protected override void OnCreate(Bundle bundle)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate(bundle);
var startup = Mvx.Resolve<IMvxAppStart>();
startup.Start();
InitializeForms(bundle);
}
}
public class Setup : MvxFormsAndroidSetup
{
public Setup():base()
{
}
protected override IEnumerable<Assembly> AndroidViewAssemblies => new List<Assembly>(base.AndroidViewAssemblies
.Union(new[] { typeof(App).GetTypeInfo().Assembly })
.Except(new[] { this.GetType().Assembly })
);
protected override Application CreateFormsApplication()
{
return new App();
}
protected override IMvxApplication CreateApp() => new CoreApp();
}
However what I started the app, its gives me null exception saying "bundle" parameter is null in OnCreated method.
P.S. The tutorial mention to create the Setup.cs, but I have no idea how does that Setup.cs being run by the code.... I see no where that is referencing it.
I'm not sure why you're looking at the version 5.5 tutorial while working with v 6.0. Try following step by step guide, from same author, but for version 6.0
You might also want to download Nick's sample, from his GitHub repo, to check how things work.
Related
I have a Xamarin Form application which has a language dropdown so user can select the application language. When user select a language I call:
CultureInfo culture = CultureInfo.CreateSpecificCulture(language);
System.Globalization.CultureInfo.CurrentUICulture = culture;
Thread.CurrentThread.CurrentCulture = culture;
Thread.CurrentThread.CurrentUICulture = culture;
AppResources.Culture = culture;
The application works fine and picks the strings from AppResources.{language}.resx
My problem is when localising an image. As per Microsoft's suggestion I have added my image to Resources/drawable folders inside the android project. In my case, I added thanks.jpg to Resources/drawable and Resources/drawable-fr. But it only shows the image on Resources/drawable folder even when I select fr-FR as language, however I found out if instead of changing the application language(culture), I change the device language, the device show the correct image(the image inside Resources/drawable-fr). I was wondering if there is any way to fix this issue.
You can create a dependence service to fix it.
First of all, create a interface.
public interface IChangeService
{
void ChangeIanguage(string lang);
}
We used it in the this format code in the xamarin forms.
<StackLayout>
<TimePicker></TimePicker>
<Image WidthRequest="100">
<Image.Source>
<OnPlatform x:TypeArguments="ImageSource">
<On Platform="iOS, Android" Value="flag.png" />
<On Platform="UWP" Value="Assets/Images/flag.png" />
</OnPlatform>
</Image.Source>
</Image>
<Button Text="Change" Clicked="Button_Clicked"></Button>
</StackLayout>
Here is background code.
public partial class LocalizedXamlPage : ContentPage
{
public LocalizedXamlPage()
{
InitializeComponent();
}
private void Button_Clicked(object sender, System.EventArgs e)
{
DependencyService.Get<IChangeService>().ChangeIanguage("en");
}
}
Then achieve the interface in the android platform. If we change the localization, we need it to work at the runtime, we should restart our application.
[assembly: Dependency(typeof(ChangeLanguageService))]
namespace UsingResxLocalization.Droid
{
public class ChangeLanguageService : IChangeService
{
public void ChangeIanguage(string lang = "in")
{
LanguageManager.ChangeLanguage(MainActivity.instance, lang);
//restart your application.
Intent intent = new Intent(MainActivity.instance, typeof(MainActivity));
intent.SetFlags(ActivityFlags.ClearTask | ActivityFlags.NewTask);
MainActivity.instance.StartActivity(intent);
}
}
}
Then we need to create a BaseActivity(because we change the Locale in android, we should use the same Context.) and LanguageManager(change the localization at the runtime)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Support.V7.App;
using Android.Views;
using Android.Widget;
using Java.Util;
using Xamarin.Forms.Platform.Android;
namespace UsingResxLocalization.Droid
{
public class BaseActivity : FormsAppCompatActivity
{
protected override void AttachBaseContext(Context #base)
{
base.AttachBaseContext(LanguageManager.LoadLanguage(#base));
}
}
public class LanguageManager
{
private const string MYLANGUAGE = "myLanguage";
private const string MYPREF = "myPreference";
public static Context LoadLanguage(Context context)
{
var loadedLanguage = GetLanguage(context, Locale.Default.Language);
return ChangeLanguage(context, loadedLanguage);
}
public static Context ChangeLanguage(Context context, string language)
{
SaveLanguage(context, language);
if (Build.VERSION.SdkInt >= BuildVersionCodes.N)
{
return ChangeForAPI24(context, language);
}
return ChangeForLegacy(context, language);
}
private static string GetLanguage(Context context, string Language)
{
var privatePreference = context.GetSharedPreferences(MYPREF, FileCreationMode.Private);
return privatePreference.GetString(MYLANGUAGE, Language);
}
private static void SaveLanguage(Context context, string language)
{
var privatePreference = context.GetSharedPreferences(MYPREF, FileCreationMode.Private);
var editor = privatePreference.Edit();
editor.PutString(MYLANGUAGE, language);
editor.Apply();
}
private static Context ChangeForAPI24(Context context, string language)
{
// for api >= 24
var locale = new Locale(language);
Locale.Default = locale;
var configuration = context.Resources.Configuration;
configuration.SetLocale(locale);
configuration.SetLayoutDirection(locale);
return context.CreateConfigurationContext(configuration);
}
private static Context ChangeForLegacy(Context context, string language)
{
var locale = new Locale(language);
Locale.Default = locale;
var resources = context.Resources;
var configuration = resources.Configuration;
configuration.Locale = locale;
resources.UpdateConfiguration(configuration, resources.DisplayMetrics);
return context;
}
}
}
To make the mainAcitvity extend the BaseActivity.cs. And expose the public static MainActivity instance;,
[Activity(Label = "UsingResxLocalization", Icon = "#mipmap/icon", Theme = "#style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
public class MainActivity : BaseActivity
{
public static MainActivity instance;
protected override void OnCreate(Bundle savedInstanceState)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
instance = this;
base.OnCreate(savedInstanceState);
global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
LoadApplication(new App());
}
}
Here is runinng GIF.
========Update=========
I make a test with France flag by changing language to fr when the device language is English.
I upload my demo to you, you can test it.
https://github.com/851265601/LocalzationDemo/blob/master/LocalzationDemoWithFlag.zip
If you want to change the text of Button or other label, when you click the Button, Please add CultureInfo.CurrentUICulture = new CultureInfo("fr", false); as well in the click event. You can see this GIF.
We have a really simple app, the idea is the timer will update a label on the home screen depending on different configuration within the mobile app. I have created the binding and can update the homepage from it's self but not from the timer. I think what is missing is a OnChange within the home page to detect if the string has changed.
Display layout code, bind the label to the name "LabelText"
<Label
Text = "{Binding LabelText, Mode=TwoWay}"
x:Name="MainPageStatusText"
HorizontalOptions="CenterAndExpand"
Grid.Row="2"
Grid.Column="0"
Grid.ColumnSpan="6"
VerticalOptions="CenterAndExpand"
TextColor="White"
FontSize="Medium"/>
This is the class file to link the text string to the label, I can see it been called from the different places but when it's called from the app.cs it does not work
using System;
using System.Collections.Generic;
using System.ComponentModel;
using Xamarin.Forms;
namespace Binding_Demo
{
public class MyClass : INotifyPropertyChanged
{
protected void OnPropertyChanged(PropertyChangedEventArgs e)
{ PropertyChanged?.Invoke(this, e); }
protected void OnPropertyChanged(string propertyName)
{ OnPropertyChanged(new PropertyChangedEventArgs(propertyName)); }
public event PropertyChangedEventHandler PropertyChanged;
private string labelText;
public string LabelText
{
get {
return labelText;
}
set
{
labelText = value;
OnPropertyChanged("LabelText");
}
}
}
}
This is the code inside the homepage, this works and I can see it sending data to the text label
public static MyClass _myClass = new MyClass();
public Homepage()
{
BindingContext = _myClass;
_myClass.LabelText = "Inside the home page";
}
This is the App.cs code, we start the timer and then want to set the text on the Homepage label. I can see the class been called, but it does not set the text.
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace Binding_Demo
{
public partial class App : Application
{
public static MyClass _myClass = new MyClass();
public App()
{
//InitializeComponent();
Device.StartTimer(TimeSpan.FromSeconds(10), () =>
{
Task.Run(() =>
{
Debug.WriteLine("Timer has been triggered");
// !!!!! This is not setting the text in the label !!!!!
BindingContext = _myClass;
_myClass.LabelText = "Inside the timer app";
});
return true; //use this to run continuously
});
MainPage = new NavigationPage(new MainPage());
}
protected override void OnStart()
{
//
}
protected override void OnSleep()
{
}
protected override void OnResume()
{
// force app to mainpage and clear the token
}
}
}
I have created the binding and can update the homepage from it's self but not from the timer.
As Jason said, please make sure the binding model is unique. You could create a global static instance of MyClass in App class, then bind this instance to HomePage.
Check the code:
App.xaml.cs
public partial class App : Application
{
public static MyClass _myClass = new MyClass();
public App()
{
InitializeComponent();
Device.StartTimer(TimeSpan.FromSeconds(5), () =>
{
Task.Run(() =>
{
_myClass.LabelText = "Inside the timer app";
});
return true;
});
MainPage = new NavigationPage(new Homepage());
}
}
Homepage.xaml.cs:
public Homepage()
{
InitializeComponent();
BindingContext = App._myClass;
}
Is there a standard cross platform way of playing a 250 ms or so 'ding' on Xamarin Forms iOS and Android?
Mark Wardell
You can use DependencyService to play default system notification sound in each platform .
Create IPlaySoundService Interface :
public interface IPlaySoundService
{
void PlaySystemSound();
}
Implement the PlaySystemSound method in iOS as follow:
[assembly: Xamarin.Forms.Dependency(typeof(PlaySoundService))]
namespace AppCarouselViewSample.iOS
{
public class PlaySoundService : IPlaySoundService
{
public void PlaySystemSound()
{
var sound = new SystemSound(1000);
sound.PlaySystemSound();
}
}
}
Implement the PlaySystemSound method in Android as follow :
[assembly:Xamarin.Forms.Dependency(typeof(PlaySoundService))]
namespace AppCarouselViewSample.Droid
{
public class PlaySoundService : IPlaySoundService
{
public void PlaySystemSound()
{
Android.Net.Uri uri = RingtoneManager.GetDefaultUri(RingtoneType.Ringtone);
Ringtone rt = RingtoneManager.GetRingtone(MainActivity.instance.ApplicationContext, uri);
rt.Play();
}
}
}
This is the definition of instance from MainActivity :
namespace xxx.Droid
{
[Activity(Label = "AppCarouselViewSample", Icon = "#mipmap/icon", Theme = "#style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
public static MainActivity instance { set; get; }
protected override void OnCreate(Bundle savedInstanceState)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate(savedInstanceState);
instance = this;
Xamarin.Forms.Forms.SetFlags(new string[] { "CarouselView_Experimental", "SwipeView_Experimental", "IndicatorView_Experimental" });
Xamarin.Essentials.Platform.Init(this, savedInstanceState);
global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
LoadApplication(new App());
}
...
}
Then it they will play the default notification Sound in each platform . You can modify SystemSoundID in iOS to fit your wants .Here is the Sound ID list .
here is my now compiling yet crashing Droid implementation
using Android.Media;
using TripCalculator.Droid.Services;
[assembly: Xamarin.Forms.Dependency(typeof(PlaySoundService))]
// Crashes
namespace TripCalculator.Droid.Services
{
public class PlaySoundService : IPlaySoundService
{
public void PlaySystemSound()
{
var currentContext = Android.App.Application.Context;
Android.Net.Uri uri = RingtoneManager.GetDefaultUri(RingtoneType.Ringtone);
Ringtone rt = RingtoneManager.GetRingtone(currentContext.ApplicationContext, uri);
rt.Play();
}
}
}
Why when I try to set ActionBar.CustomView.SetBackgroundColor (Color.White); Does the application crash?
I tried installing the ToolbarItems background via style, toolbar.axml via ResourceDictionary but not one of these methods works for me - I think because I'm too dumb.
Now this option is the easiest for me, since there is only one line of code, but somewhere you can see the conflict comes from style or toolbar.axml or something else.
ActionBar.CustomView.SetBackgroundColor (Color.White);
my app.xaml.cs
using System;
using System.IO;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using MyApp1.Services;
using MyApp1.Views;
namespace MyApp1
{
public partial class App : Application
{
static Data.TodoItemDatabase database;
public App()
{
InitializeComponent();
MainPage = new AppShell();
}
protected override void OnStart()
{
// Handle when your app start
}
protected override void OnSleep()
{
// Handle when your app sleeps
}
protected override void OnResume()
{
// Handle when your app resumes
}
public static Data.TodoItemDatabase Database
{
get
{
if (database == null)
{
database = new Data.TodoItemDatabase(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "TodoSQLite.db3"));
}
return database;
}
}
public int ResumeAtTodoId { get; set; }
}
}
Solution 1:
You can set the style of TitleView in Forms . You can create a base Navigation Pageand set the style of TitleView
<NavigationPage.TitleView>
<StackLayout Orientation="Horizontal" BackgroundColor="White" >
//...
</StackLayout>
</NavigationPage.TitleView>
Solution 2
You can try creating a Custom Renderer and set it as the base class for all pages in the app. Within this custom renderer you can try to set the background color and other style as you want in CustomTitleView .
[assembly: ExportRenderer(typeof(Page), typeof(AndroidNavigationPageRenderer )]
public class AndroidNavigationPageRenderer : PageRenderer
{
private CustomTitleView _titleView;
public NavigationSearchRenderer(Context context) : base(context)
{
}
protected override void OnElementChanged(ElementChangedEventArgs<Page> e)
{
base.OnElementChanged(e);
var activity = this.Context as FormsAppCompatActivity;
if (activity == null)
return;
var toolbar = activity.FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
_titleView= new TitleView(Context);
toolbar.AddView(_titleView);
}
}
I have business logic that loops around and does waits and other things. Currently this is in the code behind.
From what I have been able to read this is the wrong place and I should be placing this in the viewModel (correct me if wrong). If that's the case then should I have an OnAppearing method in my VM and if so how should I pass the OnAppearing to the View Model?
Currently my page OnAppearing looks like this:
protected async override void OnAppearing()
{
base.OnAppearing();
Title = Settings.mode.Text() + " Deck";
vm.LearnViewVisible = Settings.mode.IsLearn();
vm.PracticeViewVisible = Settings.mode.IsPractice();
vm.QuizViewVisible = Settings.mode.IsQuiz();
vm.QuizStartViewVisible = false;
If I am to be moving most of the business logic to the ViewModel then would that mean that all of this would move to an OnAppearing() method I create in the ViewModel?
Other way is using Behaviors.Forms from David Britch
...
<ContentPage.Behaviors>
<behaviors:EventHandlerBehavior EventName="Appearing">
<behaviors:InvokeCommandAction Command="{Binding PageAppearingCommand}" />
</behaviors:EventHandlerBehavior>
<behaviors:EventHandlerBehavior EventName="Disappearing">
<behaviors:InvokeCommandAction Command="{Binding PageDisappearingCommand}" />
</behaviors:EventHandlerBehavior>
</ContentPage.Behaviors>
...
Original
Or Xamarin Community Toolkit EventToCommandBehavior
<ContentPage.Behaviors>
<xct:EventToCommandBehavior
EventName="Appearing"
Command="{Binding PageAppearingCommand}" />
<xct:EventToCommandBehavior
EventName="Disappearing"
Command="{Binding PageDisappearingCommand}" />
</ContentPage.Behaviors>
Related Question: EventHandlerBehavior vs EventToCommandBehavior
This is how i link my Viewmodel. I would recommend setting up a ViewModelBase with : VModelActive and VModelInactive
Code Behind:
public partial class YourClass : ContentPage
{
ViewModelClass viewModelClass;
public YourClass()
{
InitializeComponent();
viewModelClass = new ViewModelClass();
this.BindingContext = viewModelClass;
}
protected override void OnAppearing()
{
base.OnAppearing();
viewModelClass.VModelActive(this, EventArgs.Empty);
}
protected override void OnDisappearing()
{
base.OnDisappearing();
viewModelClass.VModelInactive(this, EventArgs.Empty);
}
}
View Model
public override void VModelActive(Page sender, EventArgs eventArgs)
{
base.VModelActive(sender, eventArgs);
//your code
}
public override void VModelInactive(Page sender, EventArgs eventArgs)
{
base.VModelInactive(sender, eventArgs);
//your code
}
I prefer a pattern I first encountered in some Realm sample code.
A ViewModel base provides empty overrideable OnAppearing/Disappearing
public class BaseViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName] string name = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
protected bool SetProperty<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
{
if (Equals(field, value))
{
return false;
}
field = value;
OnPropertyChanged(propertyName);
return true;
}
internal virtual void OnAppearing() { }
internal virtual void OnDisappearing() { }
}
User classes descend from a base that conditionally invokes the VM.
public class BasePage : ContentPage
{
protected override void OnAppearing()
{
base.OnAppearing();
(BindingContext as BaseViewModel)?.OnAppearing();
}
protected override void OnDisappearing()
{
base.OnDisappearing();
(BindingContext as BaseViewModel)?.OnDisappearing();
}
}
// used as
public class JournalEntryDetailsViewModel : BaseViewModel
Warning: if you change the base class like this you need to use it in the XAML - use a scoped version of BasePage instead of the <ContentPage top element.
Otherwise you will get an error [CS0263] Partial declarations of 'JournalEntriesPage' must not specify different base classes
<?xml version="1.0" encoding="UTF-8"?>
<v:BasePage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:v="clr-namespace:QuickJournal.Views"
x:Class="QuickJournal.Views.JournalEntriesPage"
Title="Journal"
x:Name="page">
<ContentPage.ToolbarItems>
<ToolbarItem Text="Add" Command="{Binding AddEntryCommand}" />
</ContentPage.ToolbarItems>
<ContentPage.Content>
Here is example from my solution
public partial class TaskDetailsPage : MvvmContentPage
{
private readonly TaskDetailsViewModel _model;
public TaskDetailsPage()
{
InitializeComponent();
Shell.SetNavBarIsVisible(this, true);
Shell.SetTabBarIsVisible(this, false);
_model = BindingContext as TaskDetailsViewModel;
}
protected override string NavigationRoute => UniqeCodes.Routes.TaskDetailsPage;
protected override void OnAppearing()
{
_model.Init();
}
}