android - Is incentivised sharing allowed / possible? -

i encourage user engagement in app rewarding them once off advantage (a kind of power-up guess) when share on social media (twitter, google+ or facebook).

my first question is, considered acceptable google play store?

my next question (assuming answer first yes), how sure user has completed share not reward cancelled share intents?

my initial attempt has focussed on facebook , have set facebook sdk, registered app facebook , can complete share, others have shown share result same regardless of whether user cancelled or posted. note similar questions have been asked here , here. none of these have satisfactory solutions.

this answer sounds promising, don't recognise "session" type part of facebook sdk .

my implementation @ moment uses in fragment in response user's button press:

        if (sharedialog.canshow(sharelinkcontent.class)) {             sharelinkcontent linkcontent = new sharelinkcontent.builder()                     .setcontenttitle("my title")                     .setcontentdescription("my description.")                     .setcontenturl(uri.parse("https://play.google.com/store/apps/details?id=com.cloudforge.svn.bbarrett.floattiles"))                     .build();              mainactivity.sharedialog.show(linkcontent); 

then in main activity have method:

@override public void onactivityresult(final int requestcode, final int resultcode, final intent data) {     super.onactivityresult(requestcode, resultcode, data);     callbackmanager.onactivityresult(requestcode, resultcode, data); }    

i note debug here "resultcode" -1 when user cancels , when post.

finally in mainactivity.oncreate() method have:

    facebooksdk.sdkinitialize(this.getapplicationcontext());     callbackmanager = callbackmanager.factory.create();     sharedialog = new sharedialog(this);     sharedialog.registercallback(callbackmanager, new facebookcallback<sharer.result>() {          @override         public void onsuccess(sharer.result result) {             // todo auto-generated method stub             if(result.getpostid()!=null){                 toast.maketext(getbasecontext(), "user posted! (but never called postid null)", toast.length_long).show();             }else{                 toast.maketext(getbasecontext(), "user didn't post? (but called when have posted postid null)", toast.length_long).show();             }         }          @override         public void oncancel() {             // todo auto-generated method stub              toast.maketext(getbasecontext(), "user cancelled (but never called)", toast.length_long).show();         }          @override         public void onerror(facebookexception error) {             // todo auto-generated method stub             toast.maketext(getbasecontext(), "exception occurred", toast.length_long).show();         }          }); 

i dont think users particularly motivated share unless gain game advantage doing so, hoping can me confirm successful facebook post (i'll deal google+ , twitter next!).

thank in advance reads, upvotes , answers.