Malcolm Hall

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SwiftUI, Swift, Objective-C and iOS Development

Swift

How to use withObservationTracking to monitor an @Observable

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 Read more

By malhal, 1 year28th October 2024 ago
AppIntents

How to use SwiftData with AppIntents

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 Read more

By malhal, 2 years22nd July 2024 ago
SwiftUI

@StateObservable: A property wrapper for using an @Observable class as state without optionals or onAppear

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 Read more

By malhal, 2 years21st May 2024 ago
Concurrency

CLMonitor singleton to workaround the “Monitor named is already in use” exception

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: Read more

By malhal, 2 years15th May 2024 ago
Concurrency

A simple calculator using @Observable, withObservationTracking and AsyncStream

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 Read more

By malhal, 2 years14th May 2024 ago
Concurrency

Create an AsyncStream from withObservationTracking() function

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 Read more

By malhal, 2 years4th May 2024 ago
SwiftUI

Observable does not conform with Equatable (and Hashable)

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 Read more

By malhal, 2 years23rd April 2024 ago
SwiftUI

@Observable vs ObservableObject in SwiftUI

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 Read more

By malhal, 2 years22nd April 2024 ago
Mac

How to clone an Apple Silicon Mac without Migration Assistant or Time Machine

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 Read more

By malhal, 2 years17th April 2024 ago
SwiftUI

SwiftUI: Sharing AppStorage across the whole app

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 Read more

By malhal, 2 years10th April 2024 ago

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