When you mark a class as @Observable you can no longer use didSet because the macro converts it to a computed property, e.g. a simple: When expanded becomes: As you can see test has become a computed property that is a wrapper around a private _test property, a bit like Read more…
Reposted from: https://forums.swift.org/t/how-to-use-observation-to-actually-observe-changes-to-a-property/67591/18 I thought I’d share an example of how I am currently using it. I wanted to make an object that maintains a sorted order of the main model’s objects. I used withObservationTracking to update if either the sort order local to this object is changed or if the particular 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…
A new collapse delegate was added in Xcode 12 and iOS 14. Unfortunately the Master-Detail template was removed so there has never been a good example of how to use it to maintain the behavior of the previous template which was to show the master if no detail is showing. 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…