Conventions used

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

Code in text: 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: "Go ahead and open the project named CryptoWidget_start from the code bundle of this chapter."

A block of code is set as follows:

func doSomething(completionHandler: (Int) -> Void) {
     // perform some actions
     var result = theResultOfSomeAction
     completionHandler(result)
} 

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

func doSomething(completionHandler: (Int) -> Void) {
     // perform some actions
     var result = theResultOfSomeAction
     completionHandler(result)
} 

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: "In the project named CryptoWidget_start, go to File | New | Target | Widget Extension."

Tips or important notes

Appear like this.