Beginning Swift

By : Rob Kerr, Kåre Morstøl

4 (1)

Buy this Book

Beginning Swift

4 (1)

By: Rob Kerr, Kåre Morstøl

Buy this Book

Overview of this book

Take your first foray into programming for Apple devices with Swift.Swift is fundamentally different from Objective-C, as it is a protocol-oriented language. While you can still write normal object-oriented code in Swift, it requires a new way of thinking to take advantage of its powerful features and a solid understanding of the basics to become productive.

Beginning Swift

Contributors

Preface

Free Chapter

Swift Basics

Lesson objectives

Swift Program Structure

Swift Variables and Constants

Swift Data Types

Enums

Summary

Swift Operators and Control Flow

Lesson objectives

Swift Operators

Branching

Loops

Summary

Functions, Classes, and Structs

Lesson Objectives

Functions

Error Handling

Object-Oriented Features

Summary

Challenge

Collections

Lesson Objectives

Arrays

Sets

Dictionaries

Summary

Strings

Lesson Objectives

String Fundamentals

Using Strings

Substring

Summary

Functional Programming and Lazy Operations

Lesson Objectives

Function Type

Functional Methods

Lazy Operations

Swifty Code

Summary

Further Study

Challenge

Index

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Functional Methods

Note

Open Functional.playground at the Methods page.

Note

The following sections show different ways of performing the same tasks. They say nothing about which version is better.

filter

The filter method looks like this:

func filter(_ isIncluded: (Element) throws -> Bool) rethrows -> [Element]

It is a simple method on Sequence, and we have already used it. The input function takes an element of the sequence and returns either false or true. filter returns an array of only those elements for which the input function returns true:

let numbers = [-4,4,2,-8,0]
let negative = numbers.filter {$0<0} // [-4, -8]

Set and Dictionary have their own versions of this method, which return a Set or Dictionary respectively.

Using the filter Method

It is often simpler to use an existing collection that has everything we want, and filter it, than creating an empty collection...

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Beginning Swift

By : Rob Kerr, Kåre Morstøl

Beginning Swift

By: Rob Kerr, Kåre Morstøl

Overview of this book

Functional Methods

Note

Note

filter

Using the filter Method

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