import symbols into your program that are declared elsewhere.
GRAMMAR OF A DECLARATION
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declaration →
declarations → opt
In Swift, most declarations are also definitions in the sense that they’re implemented or initializedat the same time they’re declared, .... the distinction isn’t that important in Swift, the term declaration covers both declarations and definitions.