facebook_upload_photo.m

NSMutableDictionary* params = [[NSMutableDictionary alloc] init];
[params setObject:@"your custom message" forKey:@"message"];
[params setObject:UIImagePNGRepresentation(_image) forKey:@"picture"];
_shareToFbBtn.enabled = NO; //for not allowing multiple hits

[FBRequestConnection startWithGraphPath:@"me/photos"
                                 parameters:params
                                 HTTPMethod:@"POST"
                          completionHandler:^(FBRequestConnection *connection,
                                              id result,
                                              NSError *error) 
 {
     if (error) 
     {
         //showing an alert for failure
         [self alertWithTitle:@"Facebook" message:@"Unable to share the photo please try later."];
     } 
     else
     {
         //showing an alert for success
         [UIUtils alertWithTitle:@"Facebook" message:@"Shared the photo successfully"];
     }
     _shareToFbBtn.enabled = YES;
}];