The built-in @Query does not currently support dynamic changes, instead we can use @DynamicQuery from the SwiftDataX open-source package to achieve it. The query declaration looks like this: By default that will load all Prospect model objects, sorting them by name. If the fetchDescriptor property is later changed and this View is Read more…
SwiftUI’s design takes advantage of equality to decide if things should be updated. Measurement (backed by NSMeasurement) has something interesting in its Equatable implementation: This means that 0kg is equal to 0g despite their unit being different. This makes sense for comparing weights but not for using it to decide 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 came across this StackOverflow question How do I access the SwiftData container from outside of SwiftUI? but it turns out they needed to use the container inside an AppIntent. I knew the way to inject objects into AppIntents is via the AppDependencyManager but I’d never actually tried it with Read more…
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 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…
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…