The Swift team has recently released Swift 5.1. This version of the Swift language contains many cool features like Function Builders that are used for SwiftUI and Property Wrappers that can be used to add extra functionality to properties. This release also contains a feature called Module Stability. But what is this feature? And what does it mean to you as a developer? In this week’s blog post, I will explain this to you. But before we get to Module Stability, let’s do a little time traveling back to Swift 5.0, which shipped with ABI (Application Binary Interface) Stability. Understanding...

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If you’re into writing clean, testable and maintainable code you must have come across the term “Dependency Injection” at some point. If you’re not sure what dependency injection is, that’s okay. I will explain it briefly so we’re all on the same page before we get to the main point of this post. Dependency Injection in a Nutshell Dependency injection is the practice of making sure that no object creates or manages its own dependencies. This is best illustrated using an example. Imagine you’re building a login page for an app and you have separate service objects for registering a...

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A little while ago I wrote a post about PromiseKit. In this post I wrote mainly about how you could wrap API calls in Promises using the NSURLConnection extension that the creator of PromiseKit provides. Since writing that article I've had a bunch of people asking me more about PromiseKit. More specifically, some people wanted to know how they could wrap their existing code in Promises. To illustrate this I'm going to use Parse as an example. A regular save action in Parse Before we start making Promises, let's have a look at how you'd normally do something with Parse....

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Some of the most engaging apps we use today are apps that require network connectivity of some kind. They communicate with an API somewhere to fetch and store data for example. Or they use an API to search through a huge amount of data. The point is, you don't want your application to sit around and wait while an API call is happening. The same is true for a computing task that's heavy, for example resizing an image or storing it to disk. You want your UI to be snappy and fast. In other words, you don't want to do...

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In 2015 Apple announced Protocol extensions at WWDC and went on to explain the idea of Protocol Oriented Programming (video here), I think every iOS developer got really exited when they saw this. The ability to add default implementations to protocol methods through extensions makes it seem like everything we will ever build can and should be protocol based instead of inheritance based like we do in classical OOP. In this post, we'll explore protocols and protocol extensions to see what we can make them do. Taking advantage of Protocols today To take advantage of the awesomeness of Protocols we...

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