Min & Max integer value

BookAStar/BookAStar/Behaviors/IntegerEntryBehavior.cs

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+using Xamarin.Forms;
+
+namespace BookAStar.Behaviors
+{
+    public class IntegerEntryBehavior : Behavior<Entry>
+    {
+        public static readonly BindableProperty MinProperty = BindableProperty.Create("Min", typeof(int), typeof(IntegerEntryBehavior), 0);
+        public static readonly BindableProperty MaxProperty = BindableProperty.Create("Max", typeof(int), typeof(IntegerEntryBehavior), 0);
+
+        public int Min
+        {
+            get { return (int)GetValue(MinProperty); }
+            set { SetValue(MinProperty, value); }
+        }
+
+        public int Max
+        {
+            get { return (int)GetValue(MaxProperty); }
+            set { SetValue(MaxProperty, value); }
+        }
+
+        protected override void OnAttachedTo(Entry bindable)
+        {
+            bindable.TextChanged += bindable_TextChanged;
+        }
+
+        private void bindable_TextChanged(object sender, TextChangedEventArgs e)
+        {
+            int val;
+            if (int.TryParse(e.NewTextValue, out val))
+            {
+                IsValid = (Min > Max) || (Max >= val && val >= Min);
+            }
+            else IsValid = false;
+        }
+
+        protected override void OnDetachingFrom(Entry bindable)
+        {
+            bindable.TextChanged -= bindable_TextChanged;
+
+        }
+        public bool IsValid { get; private set; }
+    }
+}