From 1ad1df2bd8b1bc51adf05e5e7332a75710faf23b Mon Sep 17 00:00:00 2001
From: Oleg Demchenko <olegoid91@gmail.com>
Date: Thu, 28 Apr 2016 15:19:45 -0300
Subject: [PATCH] [Foundation] Add null check for Observer cback (#7)

* [Foundation] Add null check to Observer cback

* [Foundation] Rename parameter name from cback to observer
---
 src/Foundation/NSObject2.cs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/Foundation/NSObject2.cs b/src/Foundation/NSObject2.cs
index c1df9c2b5c..f79d7f9507 100644
--- a/src/Foundation/NSObject2.cs
+++ b/src/Foundation/NSObject2.cs
@@ -786,11 +786,14 @@ namespace XamCore.Foundation {
 			Action<NSObservedChange> cback;
 			NSString key;
 			
-			public Observer (NSObject obj, NSString key, Action<NSObservedChange> cback)
+			public Observer (NSObject obj, NSString key, Action<NSObservedChange> observer)
 			{
+				if (observer == null)
+					throw new ArgumentNullException (nameof(observer));
+
 				this.obj = new WeakReference (obj);
 				this.key = key;
-				this.cback = cback;
+				this.cback = observer;
 				IsDirectBinding = false;
 			}