問題：
Using storyboard this is very easy.使用故事板這很容易。 You just drag the action to "Exit".您只需將操作拖到“退出”即可。 But how should I call it from my code?但是我應該如何從我的代碼中調用它？
解決方案：
參考一： https://stackoom.com/question/qUGs參考二： How to perform Unwind segue programmatically?