Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "We can substitute Grumble wherever we would use [Pug] or Array<Pug>."

A block of code is set as follows:

let fraction = rating / total 
let ratingOutOf5 = fraction * 5 
let roundedRating = round(ratingOutOf5) // Rounds to the nearest 
  // integer.

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

class ProgrammeFetcher { 
     
    typealias FetchResultHandler = (String?, Error?) -> Void 
     
    func fetchCurrentProgrammeName(forChannel channel: Channel, 
                                   resultHandler: FetchResultHandler) { 
        // Get next programme 
        let programmeName = "Sherlock" 
        resultHandler(programmeName, nil) 
    } 

Any command-line input or output is written as follows:

$ mkdir css
$ cd css

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Select System info from the Administration panel."

Warnings or important notes appear like this.

Tips and tricks appear like this.