Published in CodeX·Sep 19, 2022Why structs are better than protocols for dependency inversionWhen we think of dependency inversion in Swift, protocols are usually the first thing that come to mind. The well known pattern is to create a protocol that defines some required behaviour and create a concrete implementation that performs that responsibility. This becomes invaluable when testing our code as we…Dependency Injection3 min readDependency Injection3 min read
Published in CodeX·Apr 12, 2022The importance of logical data modellingAs an iOS developer, I am forever shocked at how often I see fatalError(“This should never happen”) in production code. This usually arises in situations where an edge case is programatically possible, but logically impossible. The scenario Imagine a situation where I’d like an app to catalog the CDs and books on…Struct2 min readStruct2 min read
Published in CodeX·Apr 10, 2022Fun with Natural Language ProcessingI’ve recently discovered Apple’s Natural Language framework and decided to have a play, test out some ideas and share my findings. This will be a short article about a few things the framework can do and potentially offer some inspiration for your own apps I started with UITextChecker. As the…Swift2 min readSwift2 min read
Published in CodeX·Oct 22, 2021Swift + C: Callback InteroperabilityBackground A very common pattern across programming languages is the use of callback functions. A callback function is a reference to executable code passed as an argument to other code, allowing it to be executed at a later time. In swift we encounter this patten often. One particularly common example is…Swift3 min readSwift3 min read
Aug 28, 2021Tuple splatting in SwiftWhat Is Splatting? Argument splatting is the concept of extracting the parameters of an object to pass to a function automatically. In Swift this can be done using tuples. Suppose we had some data and a function that looked like this: We’d like to pass all our users through the makeGreeting function…Swift2 min readSwift2 min read
Published in CodeX·Jul 24, 2021Enums Cases as Protocol Witnesses and the Open-Closed PrincipleBackground Recently I have been implementing a lot of analytics events in a client’s app. Tagging this application (which has a great deal of UI) was always going to a laborious task, so I was looking to architect an ergonomic API to interact with. Whilst deciding on the interface I remembered…Enum2 min readEnum2 min read
Published in CodeX·Mar 26, 2021Encoding awkward types with minimal boilerplate using `withUnsafeBytes`History For many years now, the go-to way of encoding and decoding Swift types to JSON has been the Codable protocol. This gave a more type safe way of handling json than its predecessor JSONSerialization, which spat out [String: Any] dictionaries. Conversely Codable handles conversion upfront, dealing with all the type…Json2 min readJson2 min read
Published in CodeX·Mar 20, 2021Using tuples for Comparable and Equatable conformanceRecently I discovered that tuples can be used to easily and simply compare and equate multiple variables. Take for example the implementation of Date and Comparable taken from the Swift documentation: This compares the year, month and day in that order to determine which is greater…Tuples1 min readTuples1 min read
Published in CodeX·Mar 7, 2021UIGestureRecognizer with closuresOne of the biggest downsides to UIGestureRecognizer is the inability to attach simple closures in-line. To use them, a target object must be specified alongside a Selector pointing to a function to call. One major disadvantage to this paradigm is that UIGestureRecognizer only passes the calling object to the called…Uigesturerecognizer1 min readUigesturerecognizer1 min read
Published in CodeX·Feb 17, 2021Coordinators, the back button problem and a simple way to fix itBackground The Coordinator pattern has become increasingly popular recently in handling navigation through an iOS apps without tightly coupling different view controllers. There are a number of great articles that explain the various flavours of the pattern fantastically, so I’ll not rehash the same detail again. There is, however, one area…Swift2 min readSwift2 min read
