I believe this is a feature of the Swift language called Implicit Member Expression (docs here).
It’s a syntax feature that can be used to access type members in those places where Swift can determine the implied type from the context.
In order to understand how this works, it helps to look at the documentation for
Text.font() (here) and
As you can see from the documentation,
Text.font() takes an argument with an optional type of
Text.foregroundColor() takes an argument with an optional type of
Color. These will be the implied types inside the methods if implicit member expression is used.
Blue is one of the standard colors, usually accessed via
Color.blue, and title is one of the standard fonts typically accessed though its type via
Font.title. Because of implicit member expressions, these can be accessed using the shortened
.title inside of
Text.font, because Swift can tell infer what the type is for each of them based on the context. However, if it’s easier for you to read/understand, you can always always just pass in the full
Font.title, which will work exactly the same.
Hopefully this explanation helps clear up some of the confusion!