How to use @Observable in Skip Fuse? Leads to compile error, works without Skip.

[isenberg]

In my original well working SwiftUI app for iOS 17 on Swift 5 @observable combined with .onReceive(...) works fine, but when activating SKIP_ACTION = launch instead of none, it leads to this compile error:

value of type 'some View' has no member 'onReceive'
value of type '[Int]' has no member 'publisher'

Then I tried as alternative the older ObservableObject, but that failed on Skip with a different compile error, but compiles well on normal SwiftUI:

unknown attribute 'EnvironmentObject'

Reduced code derived from my larger project, now with both alternatives, which work both on non-Skip SwiftUI:

import SwiftUI
#if canImport(Observation)
import Observation
#endif

struct TestView: View {
	@Environment(TestData.self) var testData: TestData
	@EnvironmentObject var testDataObject: TestDataObject
	var body: some View {
		VStack {
			Text("\(testData.counter)")
			Text("\(testDataObject.counter)")
		}
		.onAppear() {
			logger.debug("TestView.onAppear \(testData.counter)")
		}
		.onReceive([testData.counter].publisher)  { _ in
			logger.debug("TestView.onReceive \(testData.counter)")
		}
		.onReceive([testDataObject.counter].publisher)  { _ in
			logger.debug("TestView.onReceive \(testDataObject.counter)")
		}
	}
}

@Observable class TestData {
	static let singleton = TestData()
	var counter: Int = 0
	init() {
		Task.detached() {
			while true {
				try await Task.sleep(for: .seconds(Date.now.addingTimeInterval(1).timeIntervalSinceNow))
				self.counter += 1
			}
		}
	}
}
	
class TestDataObject: ObservableObject, @unchecked Sendable {
	static let singleton = TestDataObject()
	@Published var counter: Int = 0
	init() {
		Task() {
			while true {
				try await Task.sleep(for: .seconds(Date.now.addingTimeInterval(1).timeIntervalSinceNow))
				DispatchQueue.main.async {
					self.counter += 1
				}
			}
		}
	}
}

let logger: Logger = Logger(subsystem: "testapp", category: "TestAppmodule")

/* SKIP @bridge */public struct TestAppmoduleRootView : View {
    /* SKIP @bridge */public init() {
    }
	
	public var body: some View {
		let testData = TestData.singleton
		let testDataObject = TestDataObject.singleton
		let dataModel = DataModel.singleton
		TestView()
			.environment(testData)
			.environmentObject(testDataObject)
       }
}

/* SKIP @bridge */public final class TestAppmoduleAppDelegate : Sendable {
    /* SKIP @bridge */public static let shared = TestAppmoduleAppDelegate()

    private init() {
    }

    /* SKIP @bridge */public func onInit() {
        logger.debug("onInit")
    }

    /* SKIP @bridge */public func onLaunch() {
        logger.debug("onLaunch")
    }

    /* SKIP @bridge */public func onResume() {
        logger.debug("onResume")
    }

    /* SKIP @bridge */public func onPause() {
        logger.debug("onPause")
    }

    /* SKIP @bridge */public func onStop() {
        logger.debug("onStop")
    }

    /* SKIP @bridge */public func onDestroy() {
        logger.debug("onDestroy")
    }

    /* SKIP @bridge */public func onLowMemory() {
        logger.debug("onLowMemory")
    }
}

I'll now try to convert my code to follow the example https://github.com/skiptools/skipapp-showcase/blob/main/Sources/Showcase/ObservablePlayground.swift ...
So if nobody sees a direct grave error in above, please wait until I completed the conversion to follow the ObservablePlayground example.

[isenberg]

I guess I found the root cause: My app uses Skip Fuse while the skipapp-showcase runs on Skip Lite.
Originally I selected Fuse as I like to use third party Swift modules, but will try now to switch to Lite as it looks like I can copy and modify the third part code.

[isenberg]

Following the Fuse example https://github.com/skiptools/skipapp-showcase-fuse/blob/main/Sources/ShowcaseFuse/ObservablePlayground.swift it now works fine!

Originally in my code I had the .onReceive, but it turned out to be not needed anymore and after adding more @ObservationIgnored in the larger project it works fine as I forgot about that after I had to change many private var to var to get it compiled.

[...]
public var body: some View {
		let testData = TestData.singleton
		TestView()
		    .environment(testData)
}

[...]

struct TestView: View {
	@Environment(TestData.self) var testData
	var body: some View {
		VStack {
			Text("strings: \(testData.counter)")
		}
	}
}

@Observable
class TestData {
	@ObservationIgnored static let singleton = TestData()
	var counter: Int = 0
	init() {
		Task.detached() {
			while true {
				try await Task.sleep(for: .seconds(Date.now.addingTimeInterval(1).timeIntervalSinceNow))
				self.counter += 1
			}
		}
	}
}