CODEWITHSUNDEEP
iosxamarinnsuserdefaultssharingios-app-group
L.B.
L.B.

Reputation: 11

How to call NSUserDefaults Observer from iOS-Extension in Xamarin.iOS

I try to Upload Pictures from iPhone to my Xamarin-PCL-App. I'm using a Share-Extension and iOS App-groups. My Main-App Observer on changing NSUserDefaults isn't called, when the Extension changes something.

I try to Upload Pictures from iPhone to my Xamarin-PCL-App. I'm using a Share-Extension. I already have implemented the extension, it's working fine. I can choose my App as target in the galery after klicking the share-button. The DidSelectPost() Event of the Extension is called and I can show a Message on the iPhone. Now I want to enter my Main-App to handle the incoming Picture. I added an app-group to my App and the Extension (in the entitlement.plist Files it is already there). Now I should be able to let the Main-App and the Extension communicate via NSUserDefaults, right?

I added the following Code in the Main-Apps AppDelegate in FinishedLaunching:

var userDefaults = new NSUserDefaults("group.de.companyname.appname", NSUserDefaultsType.SuiteName);
            userDefaults.AddObserver("rate", NSKeyValueObservingOptions.Prior, note =>
            {
                NSUserDefaults shared = new NSUserDefaults("group.de.companyname.appname", NSUserDefaultsType.SuiteName);
                var value = shared.ValueForKey(new NSString("rate"));
            });

It should be called on changes in NSUserDefaults key named "rate". If I change this Value in the Main-App the Event is called.

I added a simple change in the ViewContollers (Type: SLComposeServiceViewController) DidSelectPost Function:

NSUserDefaults shared = new NSUserDefaults("group.de.companyname.appname", NSUserDefaultsType.SuiteName);
shared.SetString("test", "rate");
            shared.Synchronize();

My Main-App just doesn't get the changes.

Thanks in Advance!

Upvotes: 1

Views: 686

Answers (1)

Junior Jiang
Junior Jiang

Reputation: 12723

You should AddObserver in where you changed the value, such as ViewContollers you used.

Main-Apps AppDelegate:

var userDefaults = NSUserDefaults.StandardUserDefaults;
shared.SetString("testOldData", "rate");
shared.Synchronize();

ViewContollers :

public override void ViewDidLoad ()
{
base.ViewDidLoad ();

NSUserDefaults shared = NSUserDefaults.StandardUserDefaults;
shared.AddObserver(this, "Name", NSKeyValueObservingOptions.OldNew, IntPtr.Zero);
}

//Test Changing the value
public override void ViewDidAppear(bool animated)
{ 
base.ViewDidAppear(animated);
NSUserDefaults shared = NSUserDefaults.StandardUserDefaults;
shared.SetString("testNewData", "rate");
shared.Synchronize();
}

And when value changed , this method can be invoked:

//When value cahnged this will be invoked
public override void ObserveValue(NSString keyPath, NSObject ofObject, NSDictionary change, IntPtr context)
{
    if (keyPath == "Name")
    {
        Console.WriteLine("--old--" + change.ValueForKey(new NSString("old")));
        Console.WriteLine("--new--" + change.ValueForKey(new NSString("new")));
    }
    else
        base.ObserveValue(keyPath, ofObject, change, context);
}

Upvotes: 1

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