UITextView scrolls strangely with pushViewController when use autolayout

Question

I create a UITextView with a UIToolbar in code and add it to the View of my MainViewController use Autolayout. But I find that when my MainViewController is the first screen, the UITextView does work well, if I put MainViewController after a UITableViewController, it is the second screen now, and it does not work well.

Screenshot second screen:

when I input the first t, UITextView will scroll down.

when I input the second t, UITextView will scroll up, show tt.

AppDelegate:

public override bool FinishedLaunching(UIApplication application, NSDictionary launchOptions)
{
    Window  = new UIWindow(UIScreen.MainScreen.Bounds);

    // work well
    //var navigation = new UINavigationController(new ChatViewController());

    // not work well
    var navigation = new UINavigationController(new MainViewController());

    Window.RootViewController = navigation;
    Window.MakeKeyAndVisible();

    return true;
}

ChatViewController:

public class ChatViewController:UIViewController
{
    public ChatViewController()
    {
    }

    public override void ViewDidLoad()
    {
        base.ViewDidLoad();

        // toolbar
        var toolbar = new UIToolbar(){TranslatesAutoresizingMaskIntoConstraints = false};
        toolbar.Layer.BorderColor = UIColor.LightGray.CGColor;
        toolbar.Layer.BorderWidth = 1;

        View.AddSubview(toolbar);

        toolbar.AddConstraints(NSLayoutConstraint.FromVisualFormat("V:[toolbar(==42)]", 0, "toolbar", toolbar));
        View.AddConstraints(NSLayoutConstraint.FromVisualFormat("H:|[toolbar]|", 0, "toolbar", toolbar));
        View.AddConstraints(NSLayoutConstraint.FromVisualFormat("V:[toolbar]|", 0, "toolbar", toolbar));

        // inputTextView

        var inputTextView = new UITextView(){ TranslatesAutoresizingMaskIntoConstraints = false };
        inputTextView.Font = UIFont.SystemFontOfSize(16f);
        inputTextView.Layer.BorderColor = UIColor.LightGray.CGColor;
        inputTextView.Layer.BorderWidth = 1;
        toolbar.AddSubview(inputTextView);

        toolbar.AddConstraints(NSLayoutConstraint.FromVisualFormat("V:|-[textview]-|", 0, "textview",inputTextView));
        toolbar.AddConstraints(NSLayoutConstraint.FromVisualFormat("H:|-[textview]-|", 0, "textview",inputTextView));
    }
}

MainViewController:

public class MainViewController:UITableViewController
{
    private List<string> strs;

    public MainViewController()
    {
        strs = new List<string>
        {
            "one", "two", "three"
        };
    }

    public override nint RowsInSection(UITableView tableview, nint section)
    {
        return strs.Count;
    }

    public override UITableViewCell GetCell(UITableView tableView, NSIndexPath indexPath)
    {
        var cell = tableView.DequeueReusableCell("cellId");
        cell = cell ?? new UITableViewCell(UITableViewCellStyle.Default, "cellId");
        cell.TextLabel.Text = strs[indexPath.Row];
        return cell;
    }

    public override void RowSelected(UITableView tableView, NSIndexPath indexPath)
    {
        var chatController = new ChatViewController();
        chatController.View.BackgroundColor = UIColor.White;
        NavigationController.PushViewController(chatController, true);
    }
}

Update 1

Finally I find NavigationController.PushViewController method cause the error, if I use PresentViewController method, UITextView recover normal. So how to fix this, what's wrong with PushViewController, Autolayout and UITextView?

Answer 1

Finally I find the solution from here.

3 different ways:

1. Set EdgesForExtendedLayout = UIRectEdge.None.

2. AutomaticallyAdjustsScrollViewInsets = false.

3. Create a new view and add it to the View before add my toolbar.