iOS 11 Files app integration and the UIDocumentBrowserViewController

My original article — How to Integrate Your App with Files App in iOS 11 — was published on appcoda.com.

In this tutorial I’ll show you how to embrace iOS 11’s Files app. First, I’ll walk you through configuration of an app so that any files stored in its iOS file system-based “Documents” folder are made visible in the Files app and exposed to other apps installed on your device. Second, I’ll demonstrate how you can incorporate a Files app-like interface and functionality into your own apps. All of the Swift code I wrote to accomplish these two tasks is included below — and I’ve taken lots of screenshots regarding Files app integration. Sit back, enjoy, and learn about a fundamental paradigm shift in the iOS zeitgeist, moving from a “hide-the-details” (like hiding individual files) mindset to providing users with the ability to look at and manipulate files related to their apps using a macOS Finder-like interface, except on iOS.

To pique your interest, let’s look at a feature I encoded in the final app for this tutorial. We’ll use my app, named “Document-Based App,” to view an image file in the app’s main folder:

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Swift 4 memory management via ARC for reference types (classes)

Most developers assume that Swift is a “safe” language in terms of memory management. That’s probably true most of the time, but there are some notable exceptions, especially when dealing with certain scenarios when using what are called “reference types” and “reference semantics.”

This tutorial is ultimately meant to prepare you for in-depth discussion of what seems to be inevitable shift from reference semantics to value semantics. Before I plunge into this software development paradigm shift, I want to provide you with a strong and understanding of how memory is managed when you create and use instances of the class type, a reference type. Oftentimes, reference-based memory management “just works” … until it doesn’t. Things don’t work mainly in situations where class types are designed with interdependencies and/or when multiple threads access the same instance (object) of a class type, and you get “memory leaks.” Swift manages reference-based memory with a technology Apple has dubbed “Automatic Reference Counting” (ARC). Before even begin talking about debugging memory leaks, you must understand ARC.

This discussion does not pertain to memory management for value types (struct, enum), but note that I will mention value types and value semantics several times in terms of comparison to reference types and reference semantics.

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The iOS file system in-depth (and how to be the best using critical thinking)

Have you ever wondered how all those people out there figured out how to manipulate the iOS file system in their apps? For some strange reason, Apple has never provided well-organized documentation on the subject. Here’s how I feel: “Ask and simple question and get an obtuse and overly complex answer.” There are many articles and tutorials out there, including my own, showing you examples of Objective-C or Swift code for manipulating the iOS file system, and most of the code looks basically the same. Nonetheless, this code is deceivingly complex, often underestimated, and rarely well-explained or well-understood.

Where did everybody find this boilerplate code? From simple observation, I’ve found that in many cases, developers use a copy and paste methodology, i.e., look up a few keywords in a web search engine, find the code needed on sites like StackOverflow or some blog, copy it, paste it into an Xcode project, and beat on it until it works. I don’t want you to feel this way after reading my tutorials.

I hope you’ll find it edifying and interesting to read about how I figured out how to understand and navigate the iOS file system using the “most of the code looks basically the same” boilerplates. But I bet you’ll find it even more intriguing to find that I’ve discovered an much better alternative to the boilerplate code.

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Introduction to MVVM: refactoring an MVC app using the MVVM design pattern

My original article — Introduction to MVVM: refactoring a MVC app using the MVVM design pattern — was published on appcoda.com.

[Download the Xcode 9 project from GitHub so you can follow along with my code explanation and try MVVM yourself!]

Design patterns are very important tools for iOS developers to keep in their software engineering arsenals. These patterns, along with several other best practices I’ll mention below, help developers to create reliable and maintainable apps. In other words, design patterns help in managing software complexity. In this tutorial, I’ll introduce you to the “Model-View-ViewModel” or “MVVM” design pattern. For a historical and pragmatic perspective, I’ll compare the very well-known “Model-View-Controller” or “MVC” design pattern, long favored by many iOS developers, to MVVM, which has steadily been gaining traction among the same group of developers.

In order to help you understand these design patterns, I’ll walk you through the design and coding of my app shown here:

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Introduction to iOS HealthKit with Core Bluetooth using Swift 4

My original article — Introduction to HealthKit with Core Bluetooth — was published on appcoda.com.

[Download the Xcode 9 project from GitHub so you can follow along with my code explanation and try iOS HealthKit features yourself!]

In a previous tutorial, I discussed the technology, applications, and benefits of Apple’s Core Bluetooth framework. I showed you how to build an app that wirelessly connected to a Bluetooth® heart rate monitor (HRM) — a small, portable, and “wearable” device. My sample app’s code read heart rate data from the HRM, but it didn’t do anything with the heart rate data except display it in real-time on an iPhone’s screen. While edifying and interesting, there are already a bazillion apps in the App Store that can read heart rate data, and other wearable data, using Core Bluetooth. What about doing something interesting with that data, like analyzing it, deriving value-added and meaningful results from it, and sharing it with researchers? That’s where Apple’s HealthKit framework shines. Please download the Xcode 9 project written is Swift 4 so you can follow along with my discussion.

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Controlling chaos: Error Handling in Swift 4 with do, try, catch, defer, throw, throws, Error, and NSError

[Download the Xcode 9 playground from GitHub so you can follow along with my detailed discussion and try iOS error handling using the do-try-catch feature yourself!]

This tutorial is the second in my series of tutorials on incorporating error checking into your Swift 4-based iOS apps. Remember that by “error checking,” I mean gracefully handling unexpected values, events, and conditions that arise during program execution.” Today, I’ll limit my discussion of error checking to what Swift’s authors call “Error Handling.” Please read my first, introductory article in this series if you haven’t already. I can’t emphasize enough why you need to use error checking. Remember my discussion of app quality, user intolerance of buggy apps, and the huge amount of choices consumers have? The quality of your apps represents your reputation. Do you want a bad reputation when customers choose apps largely based on reviews? They can and will vote with their fingers (and wallets) and find other apps if they don’t like your app(s). Download my Xcode 9 playground so you can follow along with my discussion, run the code, and experiment with my Swift code by making your own changes.

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Controlling chaos: Why you should care about adding error checking to your iOS apps

NOTE: The second installment of this article, “Controlling chaos: Error Handling in Swift 4 with do, try, catch, defer, throw, throws, Error, and NSError,”, has just been released.

In this tutorial, the first in a series of tutorials, we’re going to discuss the arduous topic of looking for unexpected values, events, and conditions that arise during program execution, using a technique I like to call “error checking.” Today, I’ll concentrate on the reasons why you should check for errors. I’ll mention a number of techniques I use but leave detailed discussion of those techniques and sample code to subsequent articles. The purpose of this tutorial is to convince you to make use of error checking in your apps. You ignore errors at your own dire peril. This is sink or swim. If you put out a crappy app, no one’s going to use it because you’ll get a bad reputation at Internet speed, and employers/customers will be more than happy to leave you behind forever for other app developers who aren’t too lazy to write quality code.

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Tutorial: Core Bluetooth communication with a wearable in Swift 4

The original article – Working with Core Bluetooth in iOS 11 – was published on appcoda.com.

[Download the Xcode 9 project from GitHub so you can follow along with my code explanation and try iOS Core Bluetooth features yourself!]

As iOS developers, we’re very aware that humans love connectivity. Obviously, we love to communicate with each other using wireless devices. More recently, we’ve come expect that we can communicate with what once were considered standalone, ordinary devices. We’ve come to love, even expect, that some of those wireless devices can gather and analyze data about ourselves (usually “wearables”). So many devices have become intrinsic parts of our lives that we’ve coined a now commonly-used phrase, the “Internet of Things” or “IoT.” There are now billions of wireless, communicable devices on the planet. In this tutorial, we’re going to focus on just one segment of the IoT: Bluetooth®.

I’ll explain the essential concepts behind Bluetooth® technology, show you how getting proficient in Bluetooth® software development presents you with a tremendous career opportunity, remind you that you can’t distribute an app that uses Bluetooth® without determining if you need to go through “qualification,” provide you with an overview of Apple’s Core Bluetooth framework (see also here), and finally, walk you through the development of an iOS app in Swift 4 that monitors a person’s heart rate via Core Bluetooth via a Bluetooth® device.

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iOS file management with FileManager in protocol-oriented Swift 4

NOTE: My latest tutorial has just been released, which uses the code shown herein to introduce error handling in Swift 4.

[Download the Xcode 9 project from GitHub so you can follow along with my code explanation and try iOS file management features yourself!]

How many of you have written iOS apps that work with files? I’m talking about developing apps that read, write, create, copy, move, and delete files in the app’s sandboxed file system. I’m not talking about reading an image from your app bundle so you can display it on screen, like so:

I’m talking about apps like Adobe Photoshop Express which is only useful if it can edit image files; Apple’s Pages and Numbers apps which are only useful if they can edit word processor and spreadsheet/chart files, respectively; and, Microsoft Word which is only useful if it can edit word processor documents. Yes, you can solely work from/in the cloud with all these apps, but you can also opt to store files locally on your devices. What if you open an email attachment or download a file from Safari? I guarantee you that many apps with associations to certain file extensions store those attachments or downloads locally first for editing and display, and only later sync files with iCloud or Dropbox.

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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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