Use Property wrappers on the @ObservableState properties

[hadiidbouk]

I have a Defaults property wrapper that saves and reads from user defaults.

I used to mark any property in my states with it, like the following:

@Reducer
struct MyFeature {
    struct State {
        @Defaults(key: "isDebugModeEnabled", defaultValue: false)
	var isDebugModeEnabled: Bool
    }
}

But now with the @ObservableState macro, these properties are converted to computed ones, and I cannot use my property wrapper anymore.

@Reducer
struct MyFeature {
    @ObservableState
    struct State {
        @Defaults(key: "isDebugModeEnabled", defaultValue: false)  <-- Property wrapper cannot be applied to a computed property
	var isDebugModeEnabled: Bool
    }
}

After seeing this, won't the user expect when he writes the above that the isDebugModeEnabled is a stored property?
I think this part could be confusing.

What's the recommended approach here?

[mbrandonw]

Hi @hadiidbouk, this is just an issue with Swift macros in general, in particular ones that turn a stored property into a stored+computed property duo. This affects Apple's own @Observable and @Model macros too.

There really is no universal, good solution to this problem. All I can say is that we are currently running a shared state beta right now that solves the particular problem you are having, that of backing a field with user defaults. You will be able to use it like so:

@Shared(.appStorage("isDebugModeEnabled")) var isDebugModeEnabled: Bool

So, you can either give the beta a spin now, or wait until the tools officially ship sometime in the near future.