OrchardNest

MainActor is a new attribute introduced in Swift 5.5 as a global actor providing an executor which performs its tasks on the main thread. When building apps, it’s important to perform UI updating tasks on the main thread, which can...

Swift Actors are new in Swift 5.5 and are part of the big concurrency changes at WWDC 2021. Before actors, data races were a common exception to run into. So before we dive into Actors with isolated and nonisolated access, it’s good...

Flaky tests can be frustrating to deal with. You’re ready to open your PR until you realize your tests fail on CI while they succeeded locally. You even realize your test is succeeding when executing individually, and you’re...

Static Member Lookup is extended to Generic Contexts since the release of SE-0299. It might seem to be a minor change at first, but it allows simplifying quite some code. Especially if you’re writing your views in SwiftUI,...

WWDC 2021 introduced iOS 15 with many API changes, including improvements to presenting sheets in UIKit with the new UISheetPresentationController. iOS 14 already introduced the new sheet presentation style. Still, up until iOS 15, we...

WWDC 2021 is around the corner and will bring a ton of (home)work for all of us. A new Xcode, new APIs, SwiftUI improvements, and likely a lot more things we can’t predict. WWDC is often called “Christmas for iOS...

Swift jobs are something we’re all interested in if you’re reading my articles more often. Companies are hiring remotely more than ever since everybody is working from home either way and the request for new iOS and macOS apps...

Fileprivate and private are part of the access control modifiers in Swift. These keywords, together with internal, public, and open, make it possible to restrict access to parts of your code from code in other source files and modules. The...

Property Wrappers in Swift allow you to extract common logic in a distinct wrapper object. Since the introduction during WWDC 2019 and becoming available in Xcode 11 with Swift 5 there have been many examples shared across the community....

URLSession enables you to download and upload files while the app is in the background. Basic instructions to get it working are often found online, but it’s hard to make it work as expected and debug the flows. After implementing...

NSPredicate allows us to write predicates for validating a certain outcome. They’re often used combined with Core Data fetch requests and require a certain knowledge for writing custom formats. Besides my earlier shared Unit tests,...

Observing changes in Core Data NSManagedObject instances with Combine publishers can be a great solution to keep your user interface in sync with the latest changes. After reading through my posts in the Combine and Core Data categories,...

Conditional View Modifier creation in SwiftUI allows you only to apply modifiers if a certain condition is true. Whether it’s a simple checkbox value or an OS availability check, there are many cases in which you want to apply...

Combine was introduced as a new framework by Apple at WWDC 2019. The framework provides a declarative Swift API for processing values over time and can be seen as a 1st party alternative to popular frameworks like RxSwift and...

Optionals types in Swift either have a value or not, and there are several ways to test optionals using the XCTest framework. APIs like XCTUnwrap are designed to unwrap an optional and throw an error if unwrapping failed. However, it can...

Result builders in Swift allow you to build up a result using ‘build blocks’ lined up after each other. They were introduced in Swift 5.4 and are available in Xcode 12.5 and up. Formerly known as function builders, you’ve...

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...

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...

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...

Computed properties are part of a family of property types in Swift. Stored properties are the most common which save and return a stored value whereas computed ones are a bit different. A computed property, it’s all in the name,...

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...

SwiftUI can work together with UIKit by making it easier to add SwiftUI views to UIKit and visa versa using a few extensions shared in this blog post. SwiftUI was introduced in iOS 13 at a time many of us have a big app built with UIKit....

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...

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...

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...

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...

Build performance can be analysed in Xcode to speed up Xcode builds. This can easily speed up your workflow and save a lot of time during the day. Slow builds tempt to distract us as we have to wait and jump on distractions like Twitter...

Data validation in apps is important to make sure we save data conforming to the business rules. A name should be of a certain length and can’t contain invalid characters. It’s tempting to write all this logic in a new...

Derived attributes are available since iOS 13 and aim to improve fetch performance in many different scenarios. Although we have great performance with the latest devices it’s good to be prepared for scaling up to fetching a large...

Constraints in Core Data are part of an entity configuration. Settings like the entity name and Spotlight display name might be easy to understand while constraints are a bit less known. However, they can be super useful to maintain a...

An NSManagedObject lifecycle goes from insertion and updates until deletion in the end. All those events come with their own common related modifications and can be used in many different ways. Managing state in Core Data from within the...

Marking pieces of code as available per platform or version is required in the ever changing landscape of app development. When a new Swift version or platform version arrives, we’d like to adopt to it as soon as possible. Without...