问题：
Using storyboard this is very easy.使用故事板这很容易。 You just drag the action to "Exit".您只需将操作拖到“退出”即可。 But how should I call it from my code?但是我应该如何从我的代码中调用它？
解决方案：
参考一： https://stackoom.com/question/qUGs参考二： How to perform Unwind segue programmatically?