Change return to be next/done key in Xamarin Forms Shared Project

A custom EntryRenderer can handle changing the keyboard return key description.

• iOS : UITextField has a ReturnKeyType property that you can set to a preassigned list (see UIReturnType enum).

• Android : EntryEditText has a ImeOptions property that controls what the “Action” button on the keyboard does and a SetImeActionLabel method that you can use to set any text string for it.

Usage Example of the custom Entry/EntryRenderer:

new EntryExt {
    Text = "Next Key",
    ReturnKeyType = ReturnKeyTypes.Next
},
new EntryExt {
    Text = "Done Key",
    ReturnKeyType = ReturnKeyTypes.Done
}

A Xamarin.Forms custom Entry class:

namespace YourNameSpaceHere
{
    public class EntryExt : Entry
    {
        public const string ReturnKeyPropertyName = "ReturnKeyType";

        public EntryExt() { }

        public static readonly BindableProperty ReturnKeyTypeProperty = BindableProperty.Create(
            propertyName: ReturnKeyPropertyName,
            returnType: typeof(ReturnKeyTypes),
            declaringType: typeof(EntryExt),
            defaultValue: ReturnKeyTypes.Done);

        public ReturnKeyTypes ReturnKeyType
        {
            get { return (ReturnKeyTypes)GetValue(ReturnKeyTypeProperty); }
            set { SetValue(ReturnKeyTypeProperty, value); }
        }
    }

    // Not all of these are support on Android, consult EntryEditText.ImeOptions
    public enum ReturnKeyTypes : int
    {
        Default,
        Go,
        Google,
        Join,
        Next,
        Route,
        Search,
        Send,
        Yahoo,
        Done,
        EmergencyCall,
        Continue
    }
}

iOS custom EntryRenderer:

[assembly: ExportRenderer(typeof(Entry), typeof(EntryExtRenderer_iOS))]
namespace KeyboardDone.iOS
{
    public class EntryExtRenderer_iOS : EntryRenderer
    {
        public EntryExtRenderer_iOS() { }

        protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
        {
            base.OnElementChanged(e);
            if ((Control != null) && (e.NewElement != null))
                Control.ReturnKeyType = (e.NewElement as EntryExt).ReturnKeyType.GetValueFromDescription();
        }

        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            if (e.PropertyName == EntryExt.ReturnKeyPropertyName)
            {
                D.WriteLine($"{(sender as EntryExt).ReturnKeyType.ToString()}");
                Control.ReturnKeyType = (sender as EntryExt).ReturnKeyType.GetValueFromDescription();
            }
        }
    }

    public static class EnumExtensions
    {
        public static UIReturnKeyType GetValueFromDescription(this ReturnKeyTypes value)
        {
            var type = typeof(UIReturnKeyType);
            if (!type.IsEnum) throw new InvalidOperationException();
            foreach (var field in type.GetFields())
            {
                var attribute = Attribute.GetCustomAttribute(field,
                    typeof(DescriptionAttribute)) as DescriptionAttribute;
                if (attribute != null)
                {
                    if (attribute.Description == value.ToString())
                        return (UIReturnKeyType)field.GetValue(null);
                }
                else
                {
                    if (field.Name == value.ToString())
                        return (UIReturnKeyType)field.GetValue(null);
                }
            }
            throw new NotSupportedException($"Not supported on iOS: {value}");
        }
    }
}

Android custom EntryRenderer:

[assembly: ExportRenderer(typeof(Entry), typeof(EntryExtRenderer_Droid))]
namespace KeyboardDone.Droid
{
    public class EntryExtRenderer_Droid : EntryRenderer
    {
        public EntryExtRenderer_Droid() { }

        protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
        {
            base.OnElementChanged(e);
            if ((Control != null) && (e.NewElement != null))
            {
                var entryExt = (e.NewElement as EntryExt);
                Control.ImeOptions = entryExt.ReturnKeyType.GetValueFromDescription();
                // This is hackie ;-) / A Android-only bindable property should be added to the EntryExt class 
                Control.SetImeActionLabel(entryExt.ReturnKeyType.ToString(), Control.ImeOptions);
            }
        }
        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            if (e.PropertyName == EntryExt.ReturnKeyPropertyName)
            {
                var entryExt = (sender as EntryExt);
                Control.ImeOptions = entryExt.ReturnKeyType.GetValueFromDescription();
                // This is hackie ;-) / A Android-only bindable property should be added to the EntryExt class 
                Control.SetImeActionLabel(entryExt.ReturnKeyType.ToString(), Control.ImeOptions);
            }
        }

    }
    public static class EnumExtensions
    {
        public static ImeAction GetValueFromDescription(this ReturnKeyTypes value)
        {
            var type = typeof(ImeAction);
            if (!type.IsEnum) throw new InvalidOperationException();
            foreach (var field in type.GetFields())
            {
                var attribute = Attribute.GetCustomAttribute(field,
                    typeof(DescriptionAttribute)) as DescriptionAttribute;
                if (attribute != null)
                {
                    if (attribute.Description == value.ToString())
                        return (ImeAction)field.GetValue(null);
                }
                else
                {
                    if (field.Name == value.ToString())
                        return (ImeAction)field.GetValue(null);
                }
            }
            throw new NotSupportedException($"Not supported on Android: {value}");
        }
    }
}