Month: March 2018

Protocol Oriented Programming in Swift: Advanced Applications

The original article – Protocol Oriented Programming in Swift: Is it better than Object Oriented Programming? – was published on appcoda.com.

Introduction

We’re going to talk in-depth about protocol-oriented programming (POP) using Swift 4 in this article. This post is the second and final article in a two part series. If you haven’t read the first, introductory article, please do so before continuing onwards. Today, we’ll: discuss why Swift is considered a “protocol-oriented” language, compare POP and object-oriented programming (OOP), compare value semantics and reference semantics, consider local reasoning, implement delegation with protocols, use protocols as types, use protocol polymorphism, review my real-world POP Swift code, and finally, discuss why I’ve not bought 100% into POP. Download the source code from the article so you can follow along: There are 2 playgrounds and one project on GitHub, both in Xcode 9 format and written in Swift 4.

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Protocol Oriented Programming in Swift: An Introduction

My original article — Protocol Oriented Programming in Swift: An Introduction — was published on appcoda.com.

(The second and final installment of this series is now available.)

The greatest enemy of software developers is complexity, so when I hear about new technologies promising to help me manage chaos, I listen. One of the “hot” methodologies generating much attention recently (at least since 2015) is “protocol-oriented programming” (POP) in Swift. We’ll use Swift 4 herein. While writing my own code, I’ve found POP to be promising. What’s very intriguing is Apple’s assertion that “at its heart, Swift is protocol-oriented.” I’d like to share my experiences with POP in a formal presentation, a clear and concise tutorial on this up-and-coming technology. I’ll explain the key concepts, provide plenty of code samples, make the inevitable comparison between POP and object-oriented programming (OOP), and pour cold water on the fad-oriented programming (FOP?) crowds’ claim that POP is a magic bullet solution to everything.

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Concurrency in iOS: serial and concurrent queues in Grand Central Dispatch (GCD) with Swift 4

Today, I’ll show you how to use Swift 4 and the Grand Central Dispatch (GCD) application programming interface (API) to implement the execution of (multiple) tasks in the background, i.e., parallel/concurrent execution of tasks on a multicore CPU. I’ve built a sample app that gives you two options: 1) synchronous execution of tasks in the background and 2) asynchronous execution of tasks in the background. All my Swift 4 code from this article, part of an Xcode 9 project which builds a fully-functional working sample app, is available for download here. Join me in: reviewing concurrent programming concepts; reviewing my concurrent Swift 4 code; and, examining videos of my app in action, videos of console output from my app, and the console output text itself. I’ll even show you how to graphically visualize my app’s CPU and thread usage with Xcode’s Debug Navigator.

This is a look at the app — a snapshot — after all images have finished downloading asynchronously in the background:

Here’s a video of the app downloading images asynchronously in the background:

Press the play button if you missed the first showing

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Concurrency in iOS: Introduction to the abstract Operation class and using its BlockOperation subclass to run tasks in parallel

[Download the full Xcode 9 project, written in Swift 4, from GitHub.]

Swift tutorials by iosbrain.comI’m going to introduce you to iOS concurrency with simple Swift 4 code that uses an API based on the Operation abstract class. In more complex scenarios, you would subclass and customize Operation, but iOS provides the built-in BlockOperation subclass of Operation which we’ll use here. I’ll review the tenets of concurrency, emphasize why it is necessary in almost all apps, explain the basic infrastructure of Operation, compare it to Grand Central Dispatch (GCD), and then walk you through the Swift 4 code I wrote to implement concurrency in a real-live app based on BlockOperation. I’ll even show you how to graphically visualize your app’s CPU and thread usage with Xcode’s Debug Navigator. Here’s the app that we’ll build together:

Press the play button if you missed the first showing

We now live in the day and age of writing apps that can run on devices with CPUs that have multiple cores. We can go way beyond the notion of “multitasking” as a bunch of processes vying for a “timeslice” of the CPU. We can literally run processes simultaneously on different cores. As iOS developers, it is vitally important that we understand the concept of concurrency. Why?

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Downloading and installing an old version of OS X (mac OS) on your Mac

We’re going to talk about installing a version of your Mac’s operating system (OS), known as “macOS” or “OS X,” on your Mac, older than the one you’re currently running, on a partition of your primary hard drive or on an external hard drive. You may find that your current instance of OS X is too unstable for normal day-to-day usage or more heavy-duty tasks like development. Remember all the problems people had when they upgraded to OS X 10.13, also known as “High Sierra?” Oy, vey. You might have been like “Get me the heck outta Dodge!” You wanted or needed to get back to a stable OS, like Sierra (OS X 10.12) or El Capitan (OS X 10.11). For developers, you may have to install an older version of Xcode not supported by your latest OS. For Cocoa/macOS developers, you may need to make absolutely sure that your desktop apps are backward compatible, and the only way to do that for sure is to install and run your apps on older versions of macOS. I will show you, step by step, how to get a valid copy of an older version of macOS, make a bootable installer disk, and install the old OS.

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