bitwarden-android/src/iOS/Renderers/CustomEntryRenderer.cs

using System.ComponentModel;
using Bit.iOS.Renderers;
using Bit.iOS.Utilities;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

[assembly: ExportRenderer(typeof(Entry), typeof(CustomEntryRenderer))]
namespace Bit.iOS.Renderers
{
    public class CustomEntryRenderer : EntryRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
        {
            base.OnElementChanged(e);
            if(Control != null && e.NewElement is Entry)
            {
                Control.ClearButtonMode = UITextFieldViewMode.WhileEditing;
                UpdateFontSize();
                SetBottomBorder();
            }
        }

        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            if(e.PropertyName == Entry.FontAttributesProperty.PropertyName ||
                e.PropertyName == Entry.FontFamilyProperty.PropertyName ||
                e.PropertyName == Entry.FontSizeProperty.PropertyName)
            {
                UpdateFontSize();
            }
        }

        private void UpdateFontSize()
        {
            var pointSize = iOSHelpers.GetAccessibleFont<Entry>(Element.FontSize);
            if(pointSize != null)
            {
                if(!string.IsNullOrWhiteSpace(Element.FontFamily))
                {
                    Control.Font = UIFont.FromName(Element.FontFamily, pointSize.Value);
                }
                else
                {
                    Control.Font = UIFont.FromDescriptor(UIFontDescriptor.PreferredBody, pointSize.Value);
                }
            }
        }

        private void SetBottomBorder()
        {
            Control.BorderStyle = UITextBorderStyle.None;
            var borderLine = new UIView
            {
                BackgroundColor = ((Color)Xamarin.Forms.Application.Current.Resources["BoxBorderColor"]).ToUIColor(),
                TranslatesAutoresizingMaskIntoConstraints = false
            };
            Control.AddSubview(borderLine);
            Control.AddConstraints(new NSLayoutConstraint[]
            {
                NSLayoutConstraint.Create(borderLine, NSLayoutAttribute.Height, NSLayoutRelation.Equal, 1, 1f),
                NSLayoutConstraint.Create(borderLine, NSLayoutAttribute.Leading, NSLayoutRelation.Equal,
                    Control, NSLayoutAttribute.Leading, 1, 0),
                NSLayoutConstraint.Create(borderLine, NSLayoutAttribute.Trailing, NSLayoutRelation.Equal,
                    Control, NSLayoutAttribute.Trailing, 1, 0),
                NSLayoutConstraint.Create(borderLine, NSLayoutAttribute.Top, NSLayoutRelation.Equal,
                    Control, NSLayoutAttribute.Bottom, 1, 10f),
            });
        }
    }
}