Desperately need Xamarin.IOS modal MessageBox like popup

Question

Coding in Xamarin IOS. I have a drop down list type popup, where, if The end user types in a new value, I want to ask a yes/no question: Do You want to add a new row?

The control is inside a UIStackView, which is inside a container UIView, which is in turn inside another which is presented via segue. Xamarin demanded a UIPopoverController, which I implemented. Here is The code I have so far:

using System.Threading.Tasks;
using Foundation;
using UIKit;

namespace PTPED_Engine
{

    public enum MessagePopupType
    {
        YesNo = 1,
        OKCancel = 2,
        OKOnly = 3
    }

    public enum PopupResultType
    {
        OK = 1,
        Cancel = 2,
        Yes = 3,
        No = 4
    }

    public static class AlertPopups
    {
        static NSObject nsObject;

        public static void Initialize(NSObject nsObject)
        {
            AlertPopups.nsObject = nsObject;
        }
        public static Task<PopupResultType> AskUser(UIViewController parent, UIView V, string strTitle, string strMsg, MessagePopupType mpt)
        {
            using (UIPopoverController pc = new UIPopoverController(parent))
            {
               // pc.ContentViewController
                // method to show an OK/Cancel dialog box and return true for OK, or false for cancel
                var taskCompletionSource = new TaskCompletionSource<PopupResultType>();

                var alert = UIAlertController.Create(strTitle, strMsg, UIAlertControllerStyle.ActionSheet);
                // set up button event handlers
                if (mpt == MessagePopupType.OKCancel)
                {
                    alert.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, a => taskCompletionSource.SetResult(PopupResultType.OK)));
                    alert.AddAction(UIAlertAction.Create("Cancel", UIAlertActionStyle.Default, a => taskCompletionSource.SetResult(PopupResultType.Cancel)));
                }
                if (mpt == MessagePopupType.YesNo)
                {
                    alert.AddAction(UIAlertAction.Create("Yes", UIAlertActionStyle.Default, a => taskCompletionSource.SetResult(PopupResultType.Yes)));
                    alert.AddAction(UIAlertAction.Create("No", UIAlertActionStyle.Default, a => taskCompletionSource.SetResult(PopupResultType.No)));
                }
                if (mpt == MessagePopupType.OKOnly)
                {
                    alert.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, a => taskCompletionSource.SetResult(PopupResultType.OK)));
                }
                // show it
                nsObject.InvokeOnMainThread(() =>
                {
                    pc.PresentFromRect(V.Bounds, V, UIPopoverArrowDirection.Any, true);
                });

                return taskCompletionSource.Task;
            }
        }
    }
}

and I invoke it as follows:

LookupCombo.Completed += async (object sender, CompletedEventArgs e) =>
{
    C1AutoComplete AC = (C1AutoComplete)sender;
    if (AC.Text.Trim() != "")
    {
        string sColName = AC.AccessibilityIdentifier.Trim();
        var ValuesVC = (List<Lookupcombo_Entry>)AC.ItemsSource;
        var IsThisAHit = from Lookupcombo_Entry in ValuesVC
                         where Lookupcombo_Entry.sDispVal.ToUpper().Trim() == e.value.ToUpper().Trim()
                         select Lookupcombo_Entry.sMapVal;
        if (!IsThisAHit.Any())
        {
            string sTitle = "";
            string sFull = _RM.GetString(sColName);
            if (sFull == null) { sFull = "???-" + sColName.Trim(); }
            sTitle = " Add New " + sFull.Trim() + "?";
            string sPPrompt = "Do you want to add a new " + sFull.Trim() + " named " + AC.Text.Trim() + " to the Database?";
            var popupResult = await AlertPopups.AskUser(CurrentViewController(), V, sTitle, sPPrompt, MessagePopupType.YesNo);
          }
    }
};

CurrentViewController is defined like this:

    private UIViewController CurrentViewController()
    {
        var window = UIApplication.SharedApplication.KeyWindow;
        var vc = window.RootViewController;
        while (vc.PresentedViewController != null)
        {
            vc = vc.PresentedViewController;
        }
        return vc;
    }

This does nothing. It hangs The user interface.

This should be built in, but it is only built in in Xamarin.Forms, which I do not want to use.

I have no problem in doing this stuff with an await, but this is simply not working. Can anyone help?

Thanks!

Answer 1

You can just use the ACR UserDialogs library: https://github.com/aritchie/userdialogs

Answer 2

This is a solution I provided a few years ago, I think it is an ugly hack, compared to your elegant approach. You did not say what part does not work exactly, that might help spot the problem.

Here is my solution from a few years back:

iphone UIAlertView Modal