Bug 14225 - KVC Compliant Class / Observer not notified
Summary: KVC Compliant Class / Observer not notified
Alias: None
Product: iOS
Classification: Xamarin
Component: XI runtime ()
Version: 6.4.0
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2013-08-24 08:08 UTC by StephaneC
Modified: 2017-05-19 16:56 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

AppDelegate.cs (2.78 KB, text/plain)
2017-05-19 16:56 UTC, Rolf Bjarne Kvinge [MSFT]

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Description StephaneC 2013-08-24 08:08:09 UTC
I create a KVC compliant class.

    public class KVCCompliant : NSObject
        public KVCCompliant()

        public string HelloWorld

I instantiate an object and add an observer to it.

    KVCCompliant compliant = new KVCCompliant();
    compliant.AddObserver(this, (NSString)"HelloWorld", NSKeyValueObservingOptions.OldNew, IntPtr.Zero);

Then I set the HelloWorld property.

    compliant.SetValueForKey((NSString)"Hello Steve", (NSString)"HelloWorld");
    compliant.HelloWorld = "Hello Steve Ballmer";

The observer is notified when calling SetValueForKey but not when using property setter.

In Objective-C, the observer is notified in both cases.

Same problem with Xamarin.Mac.
Comment 1 Rolf Bjarne Kvinge [MSFT] 2017-05-19 16:56:39 UTC
You must manually notify property changes:

public class KVCCompliant : NSObject
	string hello_world;

	[Export ("HelloWorld")]
	public string HelloWorld {
		get {
			return hello_world;
		set {
			base.WillChangeValue ("HelloWorld");
			hello_world = value;
			base.DidChangeValue ("HelloWorld");

this works fine for me. I've attached a complete sample file.
Comment 2 Rolf Bjarne Kvinge [MSFT] 2017-05-19 16:56:57 UTC
Created attachment 22315 [details]