facebook post a image on wall

 NSMutableDictionary *params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                   userImgView.image, @"picture",
                                   nil];
   
    [[AppDelegate sharedAppDelegate].facebook requestWithGraphPath:@"me/photos"
                         andParams:params
                     andHttpMethod:@"POST"
                       andDelegate:self];