Health warning: In general I would not recommend this approach. View data should be @State simple values or custom structs with mutating func for testable logic, passed down as let for read only, computed vars for transforming, or @Binding var for read/write. @Observable is designed for data models, e.g. loading 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
I noticed a snag when using NavigationLink(value:label:) and .navigationDestination(for:destination:) with the new @Observable vs the old Combine ObservableObject (which “just worked™️”). There are 2 compilation errors: Fortunately it is relatively simple to add Hashable conformance to an @Observable class by implementing a static func == and a func hash that Read more
In SwiftIUI, when requiring the reference semantics of a class and wanting to upgrade from Combine’s ObservableObject and @StateObject to the new @Observable it requires a bit more work to get the life-cycle correct. The reason for this is we have to store the object in @State which is designed Read more
Today I successfully cloned my M1 MacBook Air to a new M3 MacBook Pro, it took some effort so thought I would share the steps here. Before I begin, the reason I prefer to clone rather than use Migration Assistant is I have many command line tools installed all over Read more
Sharing @AppStorage without having to pass it into every feature of the app is simply done in the same way it’s done for anything else you want to share: EnvironmentKey. It lets you share a source of truth into a View hierarchy without needing to pass it into every View. 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