Swift

Existential any allows you to define existential types in Swift by prefixing a type with the any keyword. In short, an existential means "any type, but conforming to protocol X." Any and AnyView have different purposes, which I explain in my article AnyObject, Any, and any: When to use which? ...

The some keyword in Swift declares opaque types, and Swift 5.1 introduced it with support for opaque result types. Many engineers experience working with opaque types for the first time when writing a body of a SwiftUI view. Though, it's often unclear what some keyword does and when to use ...

SKStoreReviewController allows asking your users for App Store ratings from within the app. Positive ratings can help your app stand out in the App Store and attract more users. Conversions can increase when you ask the user for a rating at the right time. While implementing rating requests is easy, ...

Memory leaks often happen without notice. Although best practices like using a weak reference to self inside closures help a lot, it's usually not enough to prevent you from finding a certain memory peak during the development of a project. We can use memory graph debugging or Xcode Instruments to ...

AsyncSequence is part of the concurrency framework and the SE-298 proposal. Its name implies it's a type providing asynchronous, sequential, and iterated access to its elements. In other words: it's an asynchronous variant of the regular sequence we're familiar with in Swift. Like you won't often create your custom Sequence ...

AsyncThrowingStream and AsyncStream are part of the concurrency framework introduced in Swift 5.5 due to SE-314. Async streams allow you to replace existing code that is based on closures or Combine publishers. Before diving into details around throwing streams, I recommend reading my article covering async-await if you didn't do ...

The MetricKit framework allows us to collect all kinds of data from our end users, including launch times and hang rates. MetricKit data can be explored by going into the Xcode organizer panel in which several metrics are listed. Several techniques exist to improve launch times, but it all starts ...

AnyObject and Any got a new option any as introduced in SE-355, making it harder for us developers to know the differences. Each option has its use cases and pitfalls regarding when not to use them. Any and AnyObject are special types in Swift, used for type erasure, and don't ...

Marking pieces of code as available or unavailable 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 adapt to it as soon as possible. Without throwing away support for older versions we can make ...

Self-documenting code helps explain a piece of code to other developers on a project without the need for actual documentation. The readability of our code is an essential part of making code easier to understand for developers that didn't write the code. You could argue that it's even crucial for ...

Tasks in Swift are part of the concurrency framework introduced at WWDC 2021. A task allows us to create a concurrent environment from a non-concurrent method, calling methods using async/await. When working with tasks for the first time, you might recognize familiarities between dispatch queues and tasks. Both allow dispatching ...

Guard statements in Swift allow us to implement checks into our code that prevents the current scope from continuing. When writing code, we often have certain required conditions before continuing a method. An example can be unwrapping an optional input field before submitting a form. Required conditions can be either ...