How do I read this Swift syntax? [duplicate]

Answer 1

This is called trailing closure syntax. If the last parameter of a function is a closure, it can be placed in curly braces immediately following a closing parenthesis around the previous parameters.

The get method here takes two parameters: a String and a closure with some signature like (Request) -> ()

https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Closures.html#//apple_ref/doc/uid/TP40014097-CH11-ID102

You'll also see cases where the only parameter is a closure, like the map() method on an array. In these situations, the parentheses can be omitted entirely and the closure is written in curly braces immediately following the function name, e.g.:

let lowerCasedWords = arrayOfWords.map{ $0.lowercased() }