No property, bindable property, or event found for 'Converter', or mismatching type between value and property.

There is my code:

and controls:LabelIem code:

    #region RightText：右文字
    public static readonly BindableProperty RightTextProperty = BindableProperty.Create(nameof(RightText), typeof(string), typeof(LabelItem), null, propertyChanged: OnRightTextChanged);

    private static void OnRightTextChanged(BindableObject bindable, object oldValue, object newValue)
    {
        string text = newValue as string;
        var label = (LabelItem)bindable;
        label.LabelRight.Text = text;
    }

    public string RightText
    {
        get { return (string)GetValue(RightTextProperty); }
        set { SetValue(RightTextProperty, value); }
    }
    #endregion

then SexConverter definition:
///

        return ((int)value == 1) ? "男" : "女";
    }

    /// <summary>
    /// 在绑定模式为TwoWay或OneWayToSource时数据由目标流向源时调用
    /// </summary>
    /// <param name="value"></param>
    /// <param name="targetType"></param>
    /// <param name="parameter"></param>
    /// <param name="culture"></param>
    /// <returns></returns>
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return null;
    }
}

Why compile is wrong??::
No property, bindable property, or event found for 'Converter', or mismatching type between value and property.

The error occurred:
RightText="{Binding Model.Sex,Converter={Binding SexConverter}}"

thanks

Hello,

I have create an Enum Picker to used enum in pickers.
I don't understand why my first pick on the Picker not raised the property changed.

I attach the example at this post.

MainPage.cs

namespace TwoWayEnumPicker
{
    public partial class MainPage : ContentPage
    {
        MainPageVM view_model;

        public MainPage()
        {
            this.BindingContext = this.view_model = new MainPageVM();
            InitializeComponent();
        }
    }
}

MainPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:TwoWayEnumPicker"
             xmlns:controls="clr-namespace:TwoWayEnumPicker.Controls"
             x:Class="TwoWayEnumPicker.MainPage">


    <StackLayout>
        <Frame Margin="100" VerticalOptions="Center">
            <StackLayout Orientation="Horizontal">
                <controls:EnumBindableDescriptionPicker x:TypeArguments="local:OSType"
                                                    SelectedItem="{Binding OSType, Mode=TwoWay}"
                                                    Title="Enum List"
                                                    VerticalOptions="CenterAndExpand" />

                <Label Text="{Binding OSType, Mode=OneWay}" VerticalOptions="CenterAndExpand" />
            </StackLayout>
        </Frame>

        <Frame Margin="100" VerticalOptions="Center">
            <StackLayout Orientation="Horizontal">
                <Picker ItemsSource="{Binding ElementsList}" SelectedItem="{Binding SelectedElement, Mode=TwoWay}" Title="Standart List" />

                <Label Text="{Binding SelectedElement, Mode=OneWay}" VerticalOptions="CenterAndExpand" />
            </StackLayout>
        </Frame>

    </StackLayout>

</ContentPage>

MainPageVM.cs

namespace TwoWayEnumPicker
{
    class MainPageVM : INotifyPropertyChanged
    {
        private static readonly List<string> _elements_list = new List<string>()
        {
            "is not raised",
            "is raised"
        };
        public List<string> ElementsList => _elements_list;

        private string _selected_element;
        public string SelectedElement
        {
            get => this._selected_element;
            set
            {
                this._selected_element = value;
                this.OnPropertyChanged("SelectedElement");
            }
        }

        private OSType? _os_type;
        public OSType? OSType
        {
            get => this._os_type;
            set
            {
                this._os_type = value;
                this.OnPropertyChanged("OSType");
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        internal virtual void OnPropertyChanged(string property_name)
        {
            if (this.PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(property_name));
        }
    }
}

OSType.cs

namespace TwoWayEnumPicker
{

    public enum OSType
    {
        [Description("EDL d'entrée")]
        ArrivalEDL,
        [Description("EDL de sortie")]
        ExitEDL
    }
}

Controls/EnumBindableDescriptionPicker.cs

namespace TwoWayEnumPicker.Controls
{
    class EnumBindableDescriptionPicker<T> : Picker where T : struct
    {
        public EnumBindableDescriptionPicker()
        {
            SelectedIndexChanged += onSelectedIndexChanged;
            foreach (var value in Enum.GetValues(typeof(T))) Items.Add(getEnumDescription(value));
        }

        public new static BindableProperty SelectedItemProperty =
            BindableProperty.Create(nameof(SelectedItem), typeof(T), typeof(EnumBindableDescriptionPicker<T>),
                default(T), propertyChanged: onSelectedItemChanged, defaultBindingMode: BindingMode.TwoWay);

        public new T SelectedItem
        {
            get => (T)GetValue(SelectedItemProperty);
            set => SetValue(SelectedItemProperty, value);
        }

        private void onSelectedIndexChanged(object sender, EventArgs eventArgs)
        {
            if (SelectedIndex < 0 || SelectedIndex > Items.Count - 1)
            {
                SelectedItem = default(T);
                return;
            }
            if (!Enum.TryParse(Items[SelectedIndex], out T match))
            {
                match = getEnumByDescription(Items[SelectedIndex]);
            }
            SelectedItem = (T)Enum.Parse(typeof(T), match.ToString());
        }

        private static void onSelectedItemChanged(BindableObject bindable, object old_value, object new_value)
        {
            if (new_value == null) return;
            if (bindable is EnumBindableDescriptionPicker<T> picker) picker.SelectedIndex = picker.Items.IndexOf(picker.getEnumDescription(new_value));
        }

        private string getEnumDescription(object value)
        {
            string result = value.ToString();
            var attribute = typeof(T).GetRuntimeField(value.ToString()).GetCustomAttributes<DescriptionAttribute>(false).SingleOrDefault();
            return attribute != null ? attribute.Description : result;
        }

        private T getEnumByDescription(string description)
        {
            return Enum.GetValues(typeof(T)).Cast<T>().FirstOrDefault(x => string.Equals(getEnumDescription(x), description));
        }
    }
}

Thanks you very much.

I have a list that has a custom control used in it, and it works great, but for some reason I can't use the control in the ListView.HeaderTemplate. I am passing in a Binding of ".", because if I don't pass anything in, it won't show the header. Anyone know how to get this to work?

My Code:

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:ctrls="clr-namespace:MyApp.Controls;assembly=MyApp" xmlns:local="clr-namespace:MyApp;assembly=MyApp" x:Class="MyApp.Views.HomePage" IsBusy="{Binding IsBusy}">
<ContentPage.Content>
        <!--- Content -->
            <StackLayout Spacing="0" VerticalOptions="FillAndExpand">
                <!--- List -->
                <ListView ItemsSource="{Binding MyList}" SeparatorVisibility="None" IsPullToRefreshEnabled="true" RefreshCommand="{Binding RefreshMyListCommand}" IsRefreshing="{Binding IsRefreshing, Mode=OneWay}" ItemAppearing="OnItemAppearing" ItemSelected="OnItemSelected" RowHeight="100" Header="{Binding .}" BackgroundColor="Transparent">
                    <ListView.HeaderTemplate>
                    <DataTemplate>
                                <StackLayout Spacing="0" BackgroundColor="Transparent">
                                <ctrls:Shadow Direction="up" EndPoint="0.7" HeightRequest="80" Opacity="1" />
                                <Label Text="Test" />
                            </StackLayout>
                            </DataTemplate>
                </ListView.HeaderTemplate>
                    <ListView.ItemTemplate>
                        <DataTemplate>
                            <ViewCell>
                                <ViewCell.View>
                                    <StackLayout>
                                        <ctrls:Shadow Direction="up" EndPoint="0.7" HeightRequest="80" Opacity="1" />
                                        <Label Text="Test" />
                                    </StackLayout>
                                </ViewCell.View>
                                </ViewCell>
                        </DataTemplate>
                    </ListView.ItemTemplate>
                </ListView>
                <!--- /List -->
            </StackLayout>
    <!--- /Content -->
</ContentPage.Content>

I was trying to get all of my icon file definitions in one place so that it would be easy to swap icon sets in the future. Since I use XAML for my page definitions, I thought I'd make a ResourceDictionary with all of my icons. Just trying to get it to work, I put one in my App.xaml file:

<?xml version="1.0" encoding="utf-8"?>
<Application xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:local="clr-namespace:MyApp"
    x:Class="MyApp.App">

    <Application.Resources>
        <ResourceDictionary>       
            <x:String x:Key="SettingsIcon">"outline_settings_white_48.png"</x:String>
            <!-- rest of file deleted for brevity -->
        </ResourceDictionary>
    </Application.Resources>
</Application>

Then in my xaml, I access it like this:

<ImageButton
    x:Name="SettingsButton"
    Source="{StaticResource SettingsIcon}"
    Clicked="GoSettings"/>

This generates a run-time error (in the application output window):

Could not load image named: {0}: "outline_settings_white_48.png"
FileImageSourceHandler: Could not find image or image file was invalid: File: "outline_settings_white_48.png"

... and of course the icon is not displayed.

If I reference the icon directly, it works just fine:

<ImageButton
    x:Name="SettingsButton"
    Source="outline_settings_white_48.png"
    Clicked="GoSettings"/>

I have tried it without the .png extension, and got the same result.

What am I doing wrong?

Thanks!

P.S. Right now I only need it to work on Android.

I followed this documentation to get started with unit testing my Xamarin.iOS app on the mac. I wanted to write unit test to assert async function to check if web service response succeeds or not. I didn't find this anywhere in google search. How do I achieve it? Any sample code for this?

This is a formated version of this question as I cannot edit it

I have this attached behavior:

    public enum TextType { Email, Phone, }
        public static class Validator
        {
               public static readonly BindableProperty TextTypeProperty = BindableProperty.CreateAttached(
            "TextType", typeof(TextType), typeof(Validator), null, propertyChanged: ValidateText);

            public static TextType GetTextType(BindableObject view)
            {
                return (TextType)view.GetValue(TextTypeProperty);
            }

            public static void SetTextType(BindableObject view, TextType textType)
            {
                view.SetValue(TextTypeProperty, textType);
            }
            private static void TextTypeChanged(BindableObject bindable, object oldValue, object newValue)
            {
                var entry = bindable as Entry;
                entry.TextChanged += Entry_TextChanged;
            }

            private static void Entry_TextChanged(object sender, TextChangedEventArgs e)
            {
                var entry = sender as Entry;
                bool isValid = false;
                switch (GetTextType(sender as Entry))
                {
                    case TextType.Email:
                        isValid = e.NewTextValue.Contains("@");
                        break;
                    case TextType.Phone:
                        isValid = Regex.IsMatch(e.NewTextValue, @"^\d+$");
                        break;
                    default:
                        break;
                }

                if (isValid)
                    entry.TextColor = Color.Default;
                else
                    entry.TextColor = Color.Red;
            }
        }

in XAML:

    <Entry beh:Validator.TextType="Email" Placeholder="Validate Email"/>

when I run the application on this page, the TextTypeChanged is not called, unless I change the defaultValue to a member of the TextType enum.

In the case of iOS the title text of Tabbed pages looks too small. Furthermore, the visual is different from device to the device. For e.g. in the case of iPhone X it is centered well, however, in the case of iPhone 8, the text is pushed to the bottom instead of central (it almost touches the bottom of the screen).

The problem is that the Title is not being set fromwithin the TabbedPage.xaml.cs, in which the several pages are set as the children to the tabbed page, but rather within the C# code of the Content pages. The Title value given to the Content page is automatically shown in the Tabbed buttons.

I have found a few sources explaining how this can be achieved by using styles in Android, but found nothing regarding the formatting of the actual tabbed page label text for iOS.

Any help will be appreciated.

I'm attempting to create and consumable native android library for in my Xamarin.Forms project, native lib is here: https://github.com/florent37/DiagonalLayout

I've created the binding library project with the exported .aar and built the project with no errors.

I've also created an Xamarin Forms library project which references the android binding library so wrap the native component. See below:

The problem I am facing is when I run the application I get this error:

System.InvalidCastException: Specified cast is not valid.

The base UI element in the native project derives from android.widget.framelayout and I am trying to use as a frame in my forms project which i cant, but its the only way I really see how:

public class XFDiagonalView : Frame { }

I would really appreciate any help to resolve this issue and to be able to wrap the Android binding library for my XF project.

Is this possible ?

Hi everyone,

Yet another binding for BrainTreePayment SDK, a PayPal service.

Please check out and report issues if any.

• iOS SDK
• iOS DropIn
• Android SDK

Cheers.

Hello guys , im new on xamarin.
I have been requested to implement push notification for android and ios on existing xamarin.form project using azure hub.
I have been reading some example and documentations but still can not make any example work.
So ... here I am asking for some advice on how to begin with this task.
Any help would be pretiated.
Regards,
Leandro.

Looking for advice on how to save a file (or move a file) from app folder to a shared folder.
The users of my app enter data (SQLite) and when complete i want them to be able to export data to a text file that is created in a shared folder (like Android Download folder) so they can then do what they want with it.

my code:
string sourceFile = Path.Combine(System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal), "my.db3");

        var bytes = System.IO.File.ReadAllBytes(sourceFile);
        var fileCopyName = string.Format("/sdcard/Database_{0:dd-MM-yyyy_HH-mm-ss-tt}.db", System.DateTime.Now);
        System.IO.File.WriteAllBytes(fileCopyName, bytes);

I can copy my database to SDcard, But when I use sqlitestudio to open it, I only get empty table, no content. why? Thanks a lot.

We implemented openlayers in webview format in xamarin. And when I capture by adding capture function to xamarin,
the map part of openlayers is white and there is no response to xamarin when I use openlayer's export-png function.
I need help with this problem

capture andriod use

public async Task<byte[]> CaptureScreenAsync()
{
var activity = Xamarin.Forms.Forms.Context as MainActivity;
if (activity == null)
{
return null;
}
var view = activity.Window.DecorView;
view.DrawingCacheEnabled = true;
Bitmap bitmap = view.GetDrawingCache(true);
byte[] bitmapData;
using (var stream = new MemoryStream())
{
bitmap.Compress(Bitmap.CompressFormat.Png, 0, stream);
bitmapData = stream.ToArray();
}
return bitmapData;
}

Hello,

What Im trying to accomplish: scan the qr code -> get the data from the api -> display that in picker.

For past 2 days Im trying to accomplish following thing:

1)Get json data from my api
2) Display that to picker

Here is my JSON:

{ "20": [ ["25:1222:118.00"], ["40:1224:121.60"], ["50:1232:124.00"], ["80:1233:131.20"] ], "16": [ ["125:1223:116.00"], ["150:1225:119.00"], ["160:1226:120.20"], ["120:1538:115.40"] ], etc. etc. etc.

"20 and 16" I need to display as unique values in my Picker, while the thing I actually want to display INSIDE (the thing you pick) the picker is [this->125:1223:116.00] Thats stroke of the pneumatic cylinder, next number is ID and the last one is price.

Here is my Model I currently have and here is where my problem is:

` public class Silowniki
{
//public string Dia { get; set; }
public string Stroke { get; set; }
public string Id { get; set; }
public string Cena { get; set; }

}

public class Diameter
{
    public List<Silowniki> diameter { get; set; }
}`

My ViewModel

`public class ScannedViewModel : INotifyPropertyChanged
{
public int Quantity { get; set; }
public ObservableCollection Silowniki { get; set; }

    public string Test { get; set; }
    public Command AddTest { get; set; }
    public Command LogOut { get; set; }
    //public Command PokazListe { get; set; }

    public ScannedViewModel()
    {
        Silowniki = new ObservableCollection<Silowniki>();

        //PokazListe = new Command(() => _PokazListe(Silowniki));
        AddTest = new Command(() => TestowyProdukt(ItemOb));
        LogOut = new Command(() => _LogOut());
    }

}`

And finally (i dont know if this is the proper way) here is the code which I have after I receive the data from the api:

`ScannerPage.OnScanResult += (result) =>
{
ScannerPage.IsScanning = false;
Device.BeginInvokeOnMainThread(async () =>
{
await Navigation.PopAsync();
dynamic jsonRespone = await ConnectWithOauth.GetRequest(result.Text);
JObject parsedJson = JObject.Parse(jsonRespone);
var kk = JsonConvert.DeserializeObject(jsonRespone);
Console.WriteLine(kk);
//This below doesnt work, wanted to check if there are any elements in it..
/*
foreach (var item in kk)
{
Console.WriteLine("Pokazuje item:\n");
Console.WriteLine(item);
}
*/
SaveProducts(parsedJson, viewModel);
//My save products function
async public void SaveProducts(dynamic json, ScannedViewModel model)
{
foreach (var item in json)
{
foreach (var prop in item)
{
foreach (var test in prop)
{
Silownik = new Silowniki
{
Stroke = Convert.ToString(test[0]).Split(':')[0],
Id = Convert.ToString(test[0]).Split(':')[1],
Cena = Convert.ToString(test[0]).Split(':')[2]
};

        //Here is what Idk what to do
                    MyDia = new Diameter
                    {
                        //diameter = 
                    };
                    //Console.WriteLine(Silownik.Dia + ":" + Silownik.Cena);
                    try
                    {
                        model.ItemOb.Add(Item);
                        model.Silowniki.Add(Silownik);
                    }
                    catch (Exception e)
                    {
                        Debug.Write(e);
                    }
                }
            }
        }
        ScannedProducts nextPage = new ScannedProducts(model);
        nextPage.BindingContext = model;
        await Navigation.PushAsync(nextPage);~~~~
    }`

My function where Im getting the data:
if (response.StatusCode == HttpStatusCode.OK) { Console.WriteLine("json response"); var a = JsonConvert.DeserializeObject(responseText); return a;

I dont know what to do now.. Im really stuck.. I know how to display things from the viewModel in the xaml view, but if Im getting them in json format as I want them to be displayed I doubt if this is the right thing to do (looping through every element and creating it in the viewmodel)

Also Idk what this does: var kk = JsonConvert.DeserializeObject(jsonRespone); and how can I display it in my xaml view

From what ive read on the internet and forum here my xaml should be something like that:
<StackLayout x:Name="myStackLayout"> <Label x:Name="idKlienta" VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" /> <Picker Title="Wybierz Diameter" ItemsSource="{Binding Silowniki}" ItemDisplayBinding="{Binding Dia}"> </Picker> <Picker Title="Skok" ItemsSource="{Binding Silowniki}" ItemDisplayBinding="{Binding Id}"> </Picker></stacklayout..>

Im stuck please help me.

I connection the sqlite database by this way :

FoodData database_Food;

public static FoodData Database_Food
{
get
{

            if (database_Food == null)
            {
                database_Food = 

new FoodData(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "FoodSQLite_Test.db3"));
}

            return database_Food;
        }


    }

I search on Internet always catch the Informations about use WEBServices to connection MS SQL
its really XAMARAIN.form can only direct connection to SQLITE?

Hi, I'm new to Xamarin Android Wearables, and I want to now if I can develop an app that comsume some RestService using WIFI.
Once a have a response then y change some layout color on my Listview screen
Is that possible? Thanks

Hi everyone, I have implemented the font size with slider functionality in Xamarin Forms webview. Normally, the height of webview doesnt auto-fit content size, so I have used a custom renderer exploiting the OnPageFinished. Additionally, I used Javascript to return document.body.scrollheight and set the heightrequest of webview (since setting webview.ContentHeight was incorrect to fit the webview content).

        [assembly: ExportRenderer(typeof(ExtendedWebView), typeof(ExtendedWebViewRenderer))]
        namespace MyApp.Droid.Renderers
        {
            public class ExtendedWebViewRenderer : WebViewRenderer
            {
                public static int _webViewHeight;
                static ExtendedWebView _xwebView = null;
                WebView _webView;

                public ExtendedWebViewRenderer(Context context) : base(context)
                {
                }

                class ExtendedWebViewClient : WebViewClient
                {
                    WebView _webView;
                    public async override void OnPageFinished(WebView view, string url)
                    {
                        _webView = view;
                        if (_xwebView != null)
                        {
                            if (Build.VERSION.SdkInt >= BuildVersionCodes.Kitkat)
                            {
                                view.EvaluateJavascript("(function(){document.getElementsByTagName('body')[0].style.marginBottom = '0';return document.body.scrollHeight;})()", new MyJavaScriptResult());
                            }
                            else
                            {
                                view.LoadUrl("(function(){document.getElementsByTagName('body')[0].style.marginBottom = '0';return document.body.scrollHeight;})()");
                            }
                            int i = 10;

                            view.Settings.JavaScriptEnabled = true;

                            while (view.ContentHeight < 100 && i-- > 0)
                            {
                                await Task.Delay(100);// wait here till content is rendered
                            }
                            //_xwebView.HeightRequest = view.ContentHeight;
                            MessagingCenter.Subscribe<MyJavaScriptResult, int>(this, "SetWebViewHeight", (sender, args) =>
                             {
                    // setting webview heightrequest from javaScriptResult sent using MessagingCenter.Send
                                 _xwebView.HeightRequest = args;
                             });
                        }
                        base.OnPageFinished(view, url);
                    }

                }

                protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.WebView> e)
                {
                    base.OnElementChanged(e);
                    _xwebView = e.NewElement as ExtendedWebView;
                    _webView = Control;

                    if (e.OldElement == null)
                    {
                        _webView.SetWebViewClient(new ExtendedWebViewClient());
                    }

                }
            }

            class MyJavaScriptResult : Java.Lang.Object, IValueCallback
            {
                public MyJavaScriptResult()
                {

                }

                public void OnReceiveValue(Java.Lang.Object value)
                {
                    string jsonString = string.Empty;
                    try
                    {
                        jsonString = (string)value;
                        int result = Int32.Parse(jsonString);
                        MessagingCenter.Send(this, "SetWebViewHeight",result);
                    }
                    catch (FormatException)
                    {
                        Console.WriteLine($"Unable to parse '{jsonString}'");
                    }
                }
            }

        }

My problem is after including the font-size change feature, my height is incorrect ie., more such that blank space is seen after webview content when I increase or decrease font. I tried two possible ways I knew - (1) setting font by zooming the Android.Webkit.Webview's view.Settings.TextZoom = args; where args is given in % like zoom 100%, 150% etc.., (2) Modifying the original HtmlWebviewSource by adding style (<style> body { font-size: large/small;} </style>) in head tag dynamically and reloading the webview. Both on increasing/decreasing font leves blank space at bottom - because height is very large in (Javscript document.body.scrollheight) calculation while debugging

What I am missing..? What should I modify. Please assist. Thanks in advance

NOTE: My HTML has images and text, so I can't use HTMLlabel plugin

Hello,
When I try to run my maps application I get the following error. Event registration is overwriting existing delegate. Either just use events or your own delegate: MyApp.iOS.CustomRenderer.MapDelegate MapKit.MKMapView+_MKMapViewDelegate

I attached my CustomMapRender file to this question

I am connection to SQLITE database in this way now:
(我現在是用這個方式連到SQL)

    public static FoodData Database_Food
    {
        get
        {

            if (database_Food == null)
            {
                database_Food = new FoodData(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "FoodSQLite_Test.db3"));
            }

            return database_Food;
        }


    }

I search on Internet catch the Informations always teach use WebServices to connection MS SQL，
Its really Xamarain.Forms can only direct connection to SQLITE database?
(我在網路上都是看到用WEBservice的方式以網路連到MS資料庫
是不是XAMARAIN只能直接連SQLTE?)