Hi i am just wondering if there is a way to pop data back in xamarin forms

Question

my current code works but only so that it creates a new page instead of popping the data into the previous one

// this is where the data is getting pulled from
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;

using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace MysticsGuardian.Views
{
	[XamlCompilation(XamlCompilationOptions.Compile)]
	public partial class EmotesPage : ContentPage, INotifyPropertyChanged
	{
        ObservableCollection<EmotesModel> emotes;
        public EmotesPage()
        {
            InitializeComponent();
            emotes = new ObservableCollection<EmotesModel>
            {
                new EmotesModel {Name ="No Icon", Image="Achievement_Frame.png", Category= EmotesModel.Group.Emote},
                new EmotesModel {Name ="Guardian", Image="Police_Icon.png", Category= EmotesModel.Group.Emote},
                new EmotesModel {Name ="Guardian", Image="Danger_Icon.png", Category= EmotesModel.Group.Emote},
                new EmotesModel {Name ="Guardian", Image="Danger_Icon.png", Category= EmotesModel.Group.Emote},
                new EmotesModel {Name ="Guardian", Image="Danger_Icon.png", Category= EmotesModel.Group.Emote},
        };
			EmotesView.ItemsSource = emotes;
        }
        

        
        async void EmotesView_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            var EmoteSelected = e.CurrentSelection[0] as EmotesModel;
            var EmoteClicked = new Profile(EmoteSelected);
            await Navigation.PushModalAsync(EmoteClicked);
            
            
        }
// this is where the data goes and i would like the data to pop rather than push!

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.CommunityToolkit.UI.Views;
using Xamarin.Essentials;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using Xamarin.CommunityToolkit.Extensions;


namespace MysticsGuardian.Views
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class Profile : TabbedPage 
    {
        public Profile()
        {
            InitializeComponent();
            Emote1.Source = "Achievement_Frame.png";
            Emote2.Source = "Achievement_Frame.png";
            Emote3.Source = "Achievement_Frame.png";
            Emote4.Source = "Achievement_Frame.png";
            Emote5.Source = "Achievement_Frame.png";
        }

        async void Button_Clicked(object sender, EventArgs e)
        {
            var result = await MediaPicker.CapturePhotoAsync(new MediaPickerOptions
            {
                Title = "please pick a photo"
            });
            var stream = await result.OpenReadAsync();
            resultImage.Source = ImageSource.FromStream(() => stream);
        }
        public ObservableCollection<Image> selectedImages { get; set; }
        public ObservableCollection<Image> SelectedImages
        {
            get { return selectedImages; }
            set
            {
                selectedImages = value;
                OnPropertyChanged();
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName,string propertyName1)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName1));
        }


    private string _image1;
    private string _image2;
    private string _image3;
    private string _image4;
    private string _image5;
        public string Image1
        {
            set
            {
                if (_image1 != value)
                {
                    _image1 = value;
                    OnPropertyChanged("Image1");
                }
            }
            get
            {
                return _image1;
            }
        }
        public string Image2
        {
            set
            {
                if (_image2 != value)
                {
                    _image2 = value;
                    OnPropertyChanged("Image2");
                }
            }
            get
            {
                return _image2;
            }
        }
        public string Image3
        {
            set
            {
                if (_image3 != value)
                {
                    _image3 = value;
                    OnPropertyChanged("Image2");
                }
            }
            get
            {
                return _image3;
            }
        }
        public string Image4
        {
            set
            {
                if (_image4 != value)
                {
                    _image4 = value;
                    OnPropertyChanged("Image2");
                }
            }
            get
            {
                return _image4;
            }
        }
        public string Image5
        {
            set
            {
                if (_image5 != value)
                {
                    _image5 = value;
                    OnPropertyChanged("Image2");
                }
            }
            get
            {
                return _image5;
            }
        }
        public Profile(EmotesModel emotesModel)
        {
            InitializeComponent();
            Image1 = emotesModel.Image;
            Image2 = emotesModel.Image;
            Image3 = emotesModel.Image;
            Image4 = emotesModel.Image;
            Image5 = emotesModel.Image;
            BindingContext = this;
        }




        public void ImageButton_Clicked(object sender, EventArgs e)
        {
            Navigation.PushAsync(new EmotesPage());



        }

        public void ImageButton_Clicked_1(object sender, EventArgs e)
        {
            Navigation.PushAsync(new EmotesPage());
        }

        public void ImageButton_Clicked_2(object sender, EventArgs e)
        {
            Navigation.PushAsync(new EmotesPage());
        }

        public void ImageButton_Clicked_3(object sender, EventArgs e)
        {
            Navigation.PushAsync(new EmotesPage());
        }

        public void ImageButton_Clicked_4(object sender, EventArgs e)
        {
            Navigation.PushAsync(new EmotesPage());

        }
    

    }
}

Answer 1

Hello,

Do you want to transfer data when EmotesPage page navigate back to the Profile page?

If so, you can do this by using event call back.

Firstly, we can create a CustomEventArgs for event call back.

public class CustomEventArgs : EventArgs
    {
        private readonly string customString;
        public CustomEventArgs(string customString)
        {
            this.customString = customString;
        }
        public string CustomString
        {
            get { return this.customString; }
        }
    }

Then open your EmotesPage page, add call back event, for example, when execute EmotesView_SelectionChanged_1, you want to transfer image's source to the Profile page like following EmotesView_SelectionChanged_1, you can use  Navigation.PopAsync(); to navigate back page. And send data to the Profile page by  NaviBackEvent?.Invoke(this, new CustomEventArgs(EmoteSelected.Image));.

 public partial class EmotesPage : ContentPage
    {
        public event EventHandler<CustomEventArgs> NaviBackEvent;
        private void OnNaviBackEvent(string image)
        {
            if (NaviBackEvent != null)
            {
                NaviBackEvent(this, new CustomEventArgs(image));
            }
        }

  private async void EmotesView_SelectionChanged_1(object sender, SelectionChangedEventArgs e)
        {
            var EmoteSelected = e.CurrentSelection[0] as EmotesModel; 
           Profile EmoteClicked = new Profile(EmoteSelected);
                 await Navigation.PopAsync();
            NaviBackEvent?.Invoke(this, new CustomEventArgs(EmoteSelected.Image));
        }

Next, open your Profile page, I make a test in the Emote1 button click event, when navigate back, change the select image for imagebutton like following code.

public void ImageButton_Clicked_1(object sender, EventArgs e)
        {
            ImageButton imageButton= sender as ImageButton;
            EmotesPage emotesPage = new EmotesPage();
            emotesPage.NaviBackEvent +=(NaviSender,CustomEventArgs)=>{
                Emote1.Source = CustomEventArgs.CustomString;
            };
            Navigation.PushAsync(emotesPage);
                 }

Please note, if you use Navigation.PushAsync, you have to wrap the NavigationPage in the App.xaml.cs.

public App()
        {
            InitializeComponent();
            MainPage =new NavigationPage( new EmotesPage());
        }

Best Regards,

Leon Lu

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