ios - Posting photo on Facebook wall -

i trying post photo on facebook wall. using object graph api, not working successfully.

 if ([posttype isequal:@"photoalbum"])         {         nsstring  *imgstring=[nsstring stringwithformat:@"%@%@",imgurl,[jsonresponse valueforkey:@"imageurl"]];         nsurl *url   = [nsurl urlwithstring:imgstring];         nsdata *data = [nsdata datawithcontentsofurl:url];         uiimage  *image=[uiimage imagewithdata:data];             nsstring*postlink =[nsstring stringwithformat:@"%@",[jsonresponse valueforkey:@"postlink"]];           [dict setobject:posttitle forkey:@"message"];         [dict setobject:image forkey:@"image"];         [dict setobject:postlink forkey:@"postlink"];               [fbrequestconnection startwithgraphpath:@"me/photos" parameters:params httpmethod:@"post" completionhandler:^(fbrequestconnection *connection ,id result ,nserror *error){                 if(!error){                     nslog(@"successfull");                 }                 else{                     nslog(@"unsuccess");                 }             }];              } 

what wrong code. can please me? thanks