Those of you who’ve used Objective-C and Swift for any meaningful length of time must be familiar with the
self property of structs and classes. I’m not sure how many are aware of the
Self “type” (sometimes called a “requirement”). I would be very interested in knowing how many understand the difference between
Self. I’m talking about
self with lower-case “s,” which I’ll call “small self” herein. It’s pretty well documented. Similarly,
Self with an upper-case “S,” is what I’ll call “tall self” herein. It’s not very well documented.
Continue reading “Self versus self in Swift 4 – capital “S” and lowercase “s””
The code shown herein will only compile and link in Xcode 10 beta and run in iOS 12 beta and/or OS X 10.14 beta.
We’re in the middle of Apple’s annual product upgrade cycle and this article is the first in a series of tutorials meant to highlight the most important new features of Swift 4.2. Instead of trying to cover all of the 4.2 features/improvements in one very long article, I’m going go talk about each aspect of the new 4.2 version, one or two features at a time. (If you’re interested in more details as to why I’m focused on 4.2, see section “Swift version methodology” below.) Today, I’ll cover the
allSatisfy(_:) instance method (see also here) of the
Sequence protocol (see also here), of course intimately related to the
Collection protocol (see also here).
Continue reading “Swift 4.2 improvements to Collection and Sequence protocols with method allSatisfy”
We’re going to learn about a feature of Swift called “property observers” that help developers manage app state. You can easily add code to monitor changes to Swift native type property values as well as your own custom type property values. Remember that you can gain insight into an application by looking at its state: the data values stored in all properties of the app at a specific point in time. Getting a grip on app state, therefore managing complexity, is one of the biggest challenges in computer science. Property observers are one technology that help you get a grip. In today’s article, I’ll explain this Swift feature, demonstrate its usage with runnable examples of Swift code, show you how I built an app which relies on property observers, and provide you a list of other Swift technologies that help you manage app state and complexity. Here’s my sample app in action:
Download the Xcode 9 project and playground, both written in Swift 4, from GitHub so you can follow along with my discussion.
Continue reading “Swift 4 property observers: responding to changes in property values and managing state”