GetUserProperty extension.

Source/MQTTnet/Extensions/UserPropertyExtension.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Linq;
+
+namespace MQTTnet.Extensions
+{
+    public static class UserPropertyExtension
+    {
+        public static string GetUserProperty(this MqttApplicationMessage message, string propertyName, StringComparison comparisonType = StringComparison.OrdinalIgnoreCase)
+        {
+            return message.UserProperties.SingleOrDefault(up => up.Name.Equals(propertyName, comparisonType))?.Value;
+        }
+
+        public static T GetUserProperty<T>(this MqttApplicationMessage message, string propertyName, StringComparison comparisonType = StringComparison.OrdinalIgnoreCase)
+        {
+            return (T) Convert.ChangeType(GetUserProperty(message, propertyName, comparisonType), typeof(T));
+        }
+    }
+}

Tests/MQTTnet.Core.Tests/MqttApplicationMessage_Tests.cs

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+using System.Collections.Generic;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Extensions;
+using MQTTnet.Packets;
+
+namespace MQTTnet.Tests
+{
+    [TestClass]
+    public class MqttApplicationMessage_Tests
+    {
+        [TestMethod]
+        public void GetUserProperty_Test()
+        {
+            var message = new MqttApplicationMessage
+            {
+                UserProperties = new List<MqttUserProperty>
+                {
+                    new MqttUserProperty("foo", "bar"),
+                    new MqttUserProperty("value", "1011"),
+                    new MqttUserProperty("CASE", "insensitive")
+                }
+            };
+
+            Assert.AreEqual("bar", message.GetUserProperty("foo"));
+            Assert.AreEqual(1011, message.GetUserProperty<int>("value"));
+            Assert.AreEqual("insensitive", message.GetUserProperty("case"));
+        }
+    }
+}