iOS interface

using CoreFoundation;
using CoreNFC;
using Foundation;
using Poz1.NFCForms.Abstract;
using Poz1.NFCForms.iOS;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

[assembly: Xamarin.Forms.Dependency(typeof(NfcForms))]
namespace Poz1.NFCForms.iOS
{
    public class NfcForms : NSObject, INfcForms, INFCNdefReaderSessionDelegate
    {
        private NFCNdefReaderSession _session;
        public event EventHandler<NfcFormsTag> TagDetected;
        public void WriteTag(NdefLibrary.Ndef.NdefMessage message)
        {
            throw new NotImplementedException();
        }

        public bool IsAvailable
        {
            get
            {
                return NFCNdefReaderSession.ReadingAvailable;
            }
        }
		//Events are declared to satisfy the interface. but they dont do anything
        public event EventHandler<NfcFormsTag> TagDisconnected;
        public event EventHandler<NfcFormsTag> TagConnected;
        public event EventHandler<NfcFormsTag> NewTag;

		//actual method that does the reading, in the android part it returns an empty string as its not used by me, could be altered
        public async Task<string> ReadTag()
        {
            var reader = new NfcReader();
            var result = await reader.ScanAsync();
            if (result != null)
            {
                return result;
            }
            else
            {
                return "No messages found";
            }
        }
        public void DidInvalidate(NFCNdefReaderSession session, NSError error)
        {
			//never got thrown when i tested with 20+ different mifare ultralights
            //throw new NotImplementedException();
        }

        public void DidDetect(NFCNdefReaderSession session, NFCNdefMessage[] messages)
        {
            var bytes = messages[0].Records[0].Payload.Skip(3).ToArray();
            var message = Encoding.UTF8.GetString(bytes);
        }
    }
        public class NfcReader : NSObject, INFCNdefReaderSessionDelegate
        {
            private NFCNdefReaderSession _session;
            private TaskCompletionSource<string> _tcs;

            public Task<string> ScanAsync()
            {
                if (!NFCNdefReaderSession.ReadingAvailable)
                {
                    throw new InvalidOperationException("Reading NDEF is not available");
                }

                _tcs = new TaskCompletionSource<string>();
                _session = new NFCNdefReaderSession(this, null, true);
                _session?.BeginSession();

                return _tcs.Task;
            }

            public void DidInvalidate(NFCNdefReaderSession session, NSError error)
            {
                _tcs.TrySetException(new Exception(error?.LocalizedFailureReason));
            }

            public void DidDetect(NFCNdefReaderSession session, NFCNdefMessage[] messages)
            {
                var bytes = messages[0].Records[0].Payload.Skip(3).ToArray();
                var message = Encoding.UTF8.GetString(bytes);
                _tcs.SetResult(message);
            }
        }


}