Example of how to track in progress workflows for updates in to the app UI

WorkflowTrackingExample

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using ModernHttpClient;
using UIKit;
using ProjectTripod.Portable.Model.Messages;
using ProjectTripod.Portable.Model.Workflow;
using XamlingCore.Portable.Messages.Network;
using XamlingCore.Portable.Messages.XamlingMessenger;
using XamlingCore.Portable.View.ViewModel;
using XamlingCore.Portable.Workflow.Flow;

namespace ProjectTripod.Client.iOS.CommonViewModels.UIHelpers
{
    public class UIWorkflowWatchingViewModel : XViewModel
    {
        private readonly XWorkflowHub _hub;

        private XFlow _entryPublishFlow;
        private XFlow _tripodPublishFlow;

        List<XFlowState> _inProgressStates = new List<XFlowState>(); 

        AsyncLock _stateLock = new AsyncLock();

        public UIWorkflowWatchingViewModel(XWorkflowHub hub)
        {
            _hub = hub;
            init();
        }


       
        async void _updateFlows()
        {
            var inProgress = await _entryPublishFlow.GetInProgressItems();
            inProgress.AddRange(await _tripodPublishFlow.GetInProgressItems());

            using (var l = await _stateLock.LockAsync())
            {
                foreach (var item in inProgress)
                {
                    if (!_inProgressStates.Contains(item) && item.State != XFlowStates.Fail && item.State != XFlowStates.Success)
                    {
                        _inProgressStates.Add(item);
                        item.PropertyChanged += item_PropertyChanged;
                    }
                }
            }
           
        }

        void item_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            _processNewChanges(sender as XFlowState);
        }

        async void _processNewChanges(XFlowState state)
        {
            if (state == null)
            {
                return;
            }

            using (var l = await _stateLock.LockAsync())
            {
                if (state.State == XFlowStates.Fail || state.State == XFlowStates.Success)
                {
                    state.PropertyChanged -= item_PropertyChanged;
                    _inProgressStates.Remove(state);
                }

                if (!string.IsNullOrWhiteSpace(state.Text))
                {
                  //Show the message on the UI or something... in this casue we're firing off to somewhere else, 
                  //but you can do stuff here. 
                    new BannerMessage(GetResource(state.ParentFlow.FriendlyName), GetResource(state.Text)).Send();
                }
            }
        }



        async void init()
        {
            _entryPublishFlow = _hub.GetFlow(Workflows.SaveNewEntryToServer);
            _tripodPublishFlow = _hub.GetFlow(Workflows.NewTripod);

            while (_entryPublishFlow == null || _tripodPublishFlow == null)
            {
                await Task.Delay(1000);
                _entryPublishFlow = _hub.GetFlow(Workflows.SaveNewEntryToServer);
                _tripodPublishFlow = _hub.GetFlow(Workflows.NewTripod);
            }
            
            

            _entryPublishFlow.FlowsUpdated += _entryPublishFlow_FlowsUpdated;
            _tripodPublishFlow.FlowsUpdated += _tripodPublishFlow_FlowsUpdated;
            _updateFlows();
        }
        void _tripodPublishFlow_FlowsUpdated(object sender, EventArgs e)
        {

            _updateFlows();
        }

        void _entryPublishFlow_FlowsUpdated(object sender, EventArgs e)
        {
            _updateFlows();
        }

       

    }
}