https://www.facebook.com/groups/iostw/permalink/948649875162362/

• (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
  …..

segue.sourceViewController ///< 來源 vc
segue.destinationViewController ///< 要去的vc
}

這個segue 要不要被執行可以用

• (BOOL)shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender {
  …..
  }
  來決定