Month: May 2018

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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