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

namespace TextFieldValidation_Medium
{
  public partial class ViewController : UIViewController
  {
    private ValidationTextField _validationField;
    

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private async void EditingEnded(object sender, EventArgs args)
{
  await Validate();
}

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public async Task<ValidationState> Validate()
{
  var trigger = await RunTriggers();
  Update(trigger.State, trigger.Message); // NEW
  return trigger.State;  
}

...

private void Update(ValidationState state, string message)

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public async Task<ValidationState> Validate()
{
  var trigger = await RunTriggers();

  return trigger.State;  
}

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private async Task<Trigger> RunTriggers()
{
  // Note that the text is pulled outside of the new tasks
  var text = _textField.TextField.Text;  
  
  // neutral triggers first
  foreach(var trigger in _neutralTriggers)
  {
    if(await Task.Run(() => trigger.TriggerFunction(text)))
    {

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public class ValidationTextField
{
  ... // Private fields

  private List<Trigger> _neutralTriggers = new List<Trigger>();
  private List<Trigger> _errorTriggers = new List<Trigger>();

  ... //Public properties

  ... // Constructor

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public CGColor EditingColor { get; set; }

...

public ValidationTextField(BorderedTextField textField)
{
  ... // Initialize state colors
  
  EditingColor = _textField.BorderColor;
  _textField.TextField.EditingDidBegin += EditingBegan;

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public class ValidationTextField
{
  private BorderedTextField _textField;
  private UILabel _errorLabel; // NEW
  private CGColor _neutralStateColor;
  
  ... // State Color Properties
  
  // NEW
  public UIFont ErrorFont

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using CoreGraphics;

namespace TextFieldValidation_Medium
{
  public class ValidationTextField
  {
    private BorderedTextField _textField;
    private ValidationState _state = ValidationState.Neutral;

    public CGColor NeutralStateColor { get; set; }

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var borderedField = new BorderedTextField(NameTextField, NameTextField.TextColor.CGColor, BorderDirection.Bottom, 4);