Swift Learning of Vegetable Chicken (1): Language settings in Mac, no such module cocoa, optional type declaration

Language Settings in Mac:

No such module Cocoa: When you try Swift's tutorial to learn the code, I find that the import Cocoa has been an error when importing this package.

Because I am building a new playground project, I should import the Uikit package so that I can resolve this error

Cocoa This package is a package used in iOS development

When declaring an optional type

var mystring:string? = Nil

Note Space

The reason is I didn't notice '? ' and the position of the spaces

Fixed to

var mystring:string? = Nil

There are no spaces in the middle of a String? There is a space behind it = There is a space in the middle of nil.

Swift Learning of Vegetable Chicken (1): Language settings in Mac, no such module cocoa, optional type declaration