问题
I've been working on an OS X app in Xcode. An option that completely perplexes me is "Presentation", with the two options "Single" and "Multiple" what does this attribute do?
回答1:
So, this was actually "obvious" once I used it.
Basically, this feature causes a window to be displayed once, or multiple times if the corresponding segue in a storyboard has been triggered multiple times.
To see this in action, add a create a storyboard with a view controller in it. The place a button on the view, and an additional window controller. Create a segue between the button and the window controller to "show" the window controller.
Click on the window controller and toggle between the two Presentation options. When you run it, you will find that one case will create multiple instances of the window, while the other will create a single instance of the window.
Like I said, obvious, but had to actually use it to figure it out.
来源：https://stackoverflow.com/questions/30563367/what-is-the-difference-between-multiple-and-single-for-view-controller-prese