問題：
What is the purpose of writing comments in Swift as:在 Swift 中編寫註釋的目的是什麼：
// MARK: This is a comment
When you can also do:當您還可以執行以下操作時：
// This is a comment
What does the // MARK achieve? // MARK實現了什麼？
解決方案：
參考一： https://en.stackoom.com/question/2QteS參考二： https://stackoom.com/question/2QteS