Develop Reference

Is there a way to recommend (share) a show to your friends from an Xbox app

I am developing an UWP app for xbox one. Is it possible to share a link from my app to my friends (Facebook, Twitter...etc)?

Just take Facebook as an example, if you want to share a link from your app to Facebook, you can try to use the Facebook api. This Windows SDK for Facebook teaches you how to start and you can use FBSession.ShowFeedDialogAsync() method to share the link. About the specific steps, you can refer to this document.

WP8 Facebook send message app-to-app

My question is simple, but I cannot seem to find the answer with Google. I'm working on a Windows Phone 8 app and I would like to offer the possibility to share content with certain people in private. I will add a feature to send by SMS, but I would also like to offer the possibility to send a private message in Facebook.
There is a Facebook app for Windows Phone 8 and I wanted to know if there is a way with "App-to-app" communication to have the Facebook app send the message for me. This way, the user could edit the message and choose who to send it to, without my app having to manage this for him. I think it would be a better user experience than using the Facebook API since it would be consistent.
I looked online and there is a way to make a post. However, that's not what I want since my app handles a financial matters. Is there a simple way to do that ?

It depends not on your App but the Facebook App - if it supports such a feature.
In Windows Phone you can for example associate files and Uri's with certain Apps - MSDN source. By this it is possible (I think somehow) to pass a file (message) to other App (if that App supports it). Other problem may be where to save that file - maybe some webservice as IsolatedStorage is a bad idea.
It will be hard workaround, but surely depend mostly not on your App.
In this case I think it will be better to use Facebook API in your App.

Use Facebook to do post function like below
await Launcher.LaunchUriAsync(new Uri("fb:post?text=foo"));
Or you need implement an OAuth flow to get Facebook token then do Post by Facebook post API
https://graph.facebook.com//v2.0/me/feed?message=foo&access_token={TOKEN}
I think these are the possible ways to achieve what you want.

How to post a single tweet in C#

I am trying to post a single tweet in my Windows phone application to any twitter account. I don't want to complicate my code using external libs or APIs. If they are unavoidable, I will include. I don't need to read any tweets or need to persist my connection. Its simple, The user supplies a username, password and a tweet message and hits tweet.
The famous temple run in iPhone has exactly what I need (screenshot below).
Please guide me in C#

This is possible via XAuth. The technique is not straight forward though, your request will have to go through the Twitter API team and once they approve they will give the xAuth Access. See this other SOF answer for more details.

If you want to integrate it like in you screenshot I think you need to communicate with the API yourself.
But there is the ShareStatusTask in the Microsoft.Phone.Tasks namespace.
With that users can share your status to the social media they configured.
Also check: http://msdn.microsoft.com/en-us/library/hh394027(v=vs.92).aspx

You have two choices:
use the built-in ShareStatusTask
roll your own system.
The advantage of ShareStatusTask is that it is simple to implement and maintain.
For the user it is also a good solution as it will allow him to post the status on the social network of its choice and it avoids forcing him to authenticate again.
If you want to roll your own system, you'll have to deal with different problems:
user authentication (OAuth)
maintenance (sometimes Twitter like to change the way 3rd party apps
interact with them...)
Here is a tutorial that explains how to implement Twitter in a Windows Phone app.
Also Tweetsharp is a nice Twitter lib you can use

c# social management

I was wondering, is there a way I can create an application which for example updates both my facebook and my twitter at the same time?
So for example I have a GUI which has a similar interface as my facebook profile (or whatever), and I want to post a comment on my profile through my GUI, so I write a line in a GUI textbox, press apply and it adds the post to my facebook profile and at the same time to my twitter for example.
I know this sounds silly since u can media link both pages, but that's not my true goal, I'm just wondering if this is possible so I can extend it to other facebook services.

See
facebook API
twitter API
And (.NET related) :
C# Facebook API
C# Twitter API(unofficial)

Yes, it is definitely possible. You would have to use the APIs exposed by Facebook and Twitter. You can then post let's say status on both twitter and facebook by calling update status related APIs of both Twitter and Facebook on the apply button click event.
You can use this for Twitter and this for Facebook both are C# clients for Twitter and Facebook respectively.

Yes it is. I don't see how this wouldn't be.
Also, I suggest you have a look at Seesmic Desktop for an application that does that which use Silverlight.

How to invite users to connect to your application using Facebook Application Development interfaces

I think that this question already questioned, and probably the answer is here:
http://wiki.developers.facebook.com/index.php/Notifications.send
but the real problem is that facebook says:
Facebook discontinued support for this method March 1, 2010. Calling this method returns error code 3 -- Unknown method.
while, I couldn't find any other JS-api for the invitation,
anyone know how we can invite users, using the JS api or the .net api?
thanks.

Application-to-user and user-to-user notifications have been removed. Instead you should use counters, news (in the dashboards), or send email (to users who have granted that permission), and check out our best practices for the new communication channels.
http://wiki.developers.facebook.com/index.php/Roadmap_Notifications