Lazy collections are similar to a regular collection but change the way how modifiers like map, filter, and reduce are processed. In my experience, they haven’t got as much attention as they should as they can be more performant in certain cases. You might be more familiar with lazy vars, but have you used the …
How to use Variadic parameters in Swift
Variadic parameters make it possible to pass zero or more values of a specific type into a function. It can be a clean alternative for methods that often work with one element, and you don’t want to create an array of components for just a single value on the implementation level. The great thing about …
XCTExpectFailure: Expected test failures explained with code examples
XCTExpectFailure was introduced in Xcode 12.5 and allows marking test failures as expected. The first time I read about this new API I was kind of confused: why wouldn’t we use methods like XCTAssertThrowsError instead? I continued my journey and quickly realised this API is a welcome addition to the XCTest framework. In fact, it …
Lazy var in Swift explained with code examples
A lazy var is a property whose initial value is not calculated until the first time it’s called. It’s part of a family of properties in which we have constant properties, computed properties, and mutable properties. A lazy property might be lesser known to beginners in Swift but are actually super valuable once you know …
Closures in Swift explained with Code Examples
Closures in Swift can be challenging to understand with types like trailing closures, capturing lists, and shorthand syntaxes. They’re used throughout the standard library and are part of the basics you need to know when writing Swift code. Xcode will help us most of the time with the right syntax using autocompletion but it’s good …
SwiftLee 2020 In Review: Most read blog posts
Every year I’m looking back at what I achieved with SwiftLee as well as what I want to achieve in the upcoming year. I did this in 2018, 2019, and I’m doing the same in this blog post for 2020. 2020 is definitely not comparable to the years before due to COVID and all its …
Getting started with associated types in Swift Protocols
Associated types in Swift work closely together with protocols. You can literally see them as an associated type of a protocol: they are family from the moment you put them together. Obviously, it’s a bit more complicated to explain how associated types work but once you get the hang of it, you’ll be using them …
Result in Swift: Getting started with Code Examples
The Result enum is available since Swift 5 and allows us to define a success and failure case. The type is useful for defining the result of a failable operation in which we want to define both the value and error output type. The standard Swift library adds more functionality to the result type which …
Xcode Mark Line to improve readability using // Mark: comments
Xcode Mark Lines allows us to create a better overview of sections within our classes or structs. A so-called mark comment adds both a chapter title and linebreak in the Xcode method navigator. This chapter split makes it easier to quickly navigate through a relative big object. Even-though this technique is great and allows us …
App Launch Time: 7 tips to increase performance
App Launch Time is the time it takes before your app becomes responsive after startup. As the first experience of your user it’s important that it’s smooth and as fast as possible. A slow startup time could mean losing a lot of users which can result in less usage in your app. Even-though today’s devices …