如何在循环创建 UserControls 时解除对 UI 线程的阻塞？

Question

"RedditData" is a record where I keep a static field and property (UserClient) from which I get the FrontPage list (which in itself is a List of Post, and Post is a custom type). UserClient is of type RedditClient, from the Nuget package I use.

For now the code looks like this:

List<Post> list = new();

await Task.Run(() =>
{
   list = RedditData.UserClient.FrontPage;
});

foreach(Post post in await Task.Run (() => list))
{
  if(post is LinkPost linkPost)
  {
    UserControl userControl = new()
    {
      Title = linkPost.Title,
      Link = linkPost.Link,
      Button1ClickCommand = ICommandClick1,
      Button2ClickCommand = ICommandClick2
    };
    userControl.SetImage();
    ObservableCollectionOfUserControl.Add(userControl);
  }
  else if(post is SelfPost selfPost)
  {
     UserControl userControl = new()
    {
      Title = selfPost.Title,
      Link = selfPost.Link,
      Button1ClickCommand = ICommandClick1,
      Button2ClickCommand = ICommandClick2
    };
    //this list is used on the ItemsRepeater's ItemsSource x:Bind
    ObservableCollectionOfUserControl.Add(userControl);
  }
}

The problem with this code is that it blocks the UI while it's creating the UserControls. I got to let it show the ProgressBar moving by using await Task.Run on the foreach, but it still blocks the window from moving, resizing, etc. I can't add the foreach inside a Task.Run or a Task.Factory.StartNew because of the UI creation, and even if I did put a foreach inside a dispatcher.TryEnqueue, it'd still block the UI thread. I'm not sure what to do.

Two observations:

Post, PostType1/2 are custom types from a Nuget package,

ListOfPosts is not a local List and it's also from the Nuget package, although it is a "normal" List. It's items are caught over the internet. I've tried passing them to a local variable before creating the UserControls, thinking it was something to do with the connection, but didn't change anything.

Answer 1

ListOfPosts is not a local List and it's also from the Nuget package, although it is a "normal" List. It's items are caught over the internet. I've tried passing them to a local variable before creating the UserControls, thinking it was something to do with the connection, but didn't change anything.

This is almost certainly the problem right here. I would try converting this custom list into a normal (in-memory) list within the Task.Run . That way it won't be hitting the network on your UI thread.

Depending on the implementation, you may also need to create your own DTO type(s) and copy the list entries over to them also off the UI thread.