null converters

src/App/Utilities/IsNotNullConverter.cs

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+using System;
+using Xamarin.Forms;
+
+namespace Bit.App.Utilities
+{
+    public class IsNotNullConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter,
+            System.Globalization.CultureInfo culture)
+        {
+            if(targetType == typeof(bool))
+            {
+                return value != null;
+            }
+            throw new InvalidOperationException("The target must be a boolean.");
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter,
+            System.Globalization.CultureInfo culture)
+        {
+            throw new NotSupportedException();
+        }
+    }
+}

src/App/Utilities/IsNullConverter.cs

@@ -0,0 +1,24 @@
+using System;
+using Xamarin.Forms;
+
+namespace Bit.App.Utilities
+{
+    public class IsNullConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter,
+            System.Globalization.CultureInfo culture)
+        {
+            if(targetType == typeof(bool))
+            {
+                return value == null;
+            }
+            throw new InvalidOperationException("The target must be a boolean.");
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter,
+            System.Globalization.CultureInfo culture)
+        {
+            throw new NotSupportedException();
+        }
+    }
+}