#Swift downcast initializer how to#

Throughout this book, you’ll often use strings to collect user input and to create and format user output. String: Collections of characters (numbers, letters, and symbols).Double: Highly precise floating-point numbers that can handle a large number of digits.Float: Floating-point numbers (numbers with decimal points in them).Int: Integers (whole numbers such as 1, 0, and –99).Most basic logic that we implement in this book will take advantage of one of these data types: Swift includes a number of data types that enable you to work with common types of information. Let’s begin by taking a look at a few Swift data types and how they are declared and used. The type is either a Swift data type or the name of a class that you want to instantiate and use. I make a point of always trying to provide the variable type, but if you don’t, Swift will try to figure it out for you. Holy cow-that looks complicated! In practice, nearly everything but the var keyword and the variable name are optional. Whatever the purpose, you declare your variables using this syntax: var Nor did we talk about variables within methods! Understanding built-in swift data typesĮarlier we documented what variable properties will look like in your Swift files, but we didn’t really get into the process of how you declare them (or use them).So, this section reviews several key programming tasks that you’ll be using to implement your methods:

#Swift downcast initializer how to#

We’ve explored the notion of classes, methods, and instance variables, but you probably still don’t have a real idea of how to go about making a program do something. IOS 8 Application Development in 24 Hours, Sams Teach Yourself, 6th Edition