The UI is blocked during refresh ListView for xamarin form

Question

Why is the UI blocked when I load data from the server using an async request as follows:

public ObservableCollection<VideoFile> VideoFiles { get; private set; } = new ObservableCollection<VideoFile>();

private void LoadVideoFiles(string categoryId = "*", int page = 1)
{
    _videoFiles = NotifyTask.Create(_videoManager.GetVideoFilesAsync(_videoFileSearchParam));
    _videoFiles.PropertyChanged -= VideoFilesPropertyChanged;
    _videoFiles.PropertyChanged += VideoFilesPropertyChanged;
}

private void VideoFilesPropertyChanged(object sender, PropertyChangedEventArgs propertyName)
{
    foreach (var videoFile in ((NotifyTask<List<VideoFile>>)sender).Result)
    {
        VideoFiles.Add(videoFile);
    }
}

How those methods are invoked to do the refresh? From the code, from XAML, from View Model? — Adam Kaczmarski, Sep 17 '21 at 07:00
View model have property Category, by on change Category invoke method LoadVideoFiles parametr by category id. — Domestos, Sep 17 '21 at 08:10

Adam Kaczmarski · Accepted Answer · 2021-09-20T21:07:21.110

2

UI is being blocked because calls you are making are synchronous, thus app will wait with the whole thread until this call ends. If you want to make UI responsive in the meantime you should make method asynchronous using async keyword. This way it will let method run, while all other UI elements will stay responsive. You can read more here

edited Sep 20 '21 at 21:07

answered Sep 17 '21 at 10:49

Adam Kaczmarski

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The UI is blocked during refresh ListView for xamarin form

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