To upgrade old Combine code in an ObservableObject that had its lifetime tied to a SwiftUI View using @StateObject we can replace it with .task and since async/await gives us a lifetime like a reference type we can do away with the object altogether. In the Combine version of the Read more…
If you attempt to init another instance of CLMonitor with the same name it crashes with: Since I wanted to use the same monitor from different tasks I needed to turn it into a singleton and came up with this: This allows this kind of thing to work without crashing: Read more…
Following on from my previous post on this topic I found a forum post with someone struggling to build a calculator using @Observable and thought maybe my technique of wrapping withObservationTracking in AsyncStream might help and came up with the code below which appears to work. Obviously this code comes Read more…
I needed to create an AsyncStream to monitor changes to an @Observable model class’s var and by using withCheckedContinuation and AsyncStream‘s unfolding init I came up with this: The challenge here is withObservationTracking only watches for a single change but we can wrap that in withCheckedContinuation which also is designed Read more…
When I first used AsyncStream with merge from AsyncAlgorithms I struggled with merging different stream result types and had experimented with building a protocol that each stream’s result type enum implemented. That way all the streams used the same protocol type and could be merged. I realised today that I Read more…
Discovered this strange error in Swift, when using the sample code from the proposal which is supposed to have been accepted and implemented
I needed to show an alert in an async context and this is how I achieved it: The idea to throw a cancellation exception was inspired by DDDevicePickerViewController which is the only built-in async UIViewController I’m aware of.
Update 10/4/2024: It appears in Xcode 15.3 nothing special is required and can use await right next to the hello world print. TLDR: add @main and rename main.swift To create a command line tool in Xcode 14.3 that uses async/await there are a few tweaks required. When we create the Read more…
Seems to me some developers think that @MainActor means “always main thread” and has the same behaviour as DispatchQueue.main.async which I don’t think is try. For example, the code below outputs: Because the Database class is not marked as @MainActor then loadModel will in fact be on a background thread, Read more…