Swift UI example

[MerinoA]

This pull request adds the basic example of the 'FetchableRequest' property wrapper in a swiftUI view.

During the implementation of this example I discovered an issue when using the property wrapper. The initial data would not render on the initial render pass.

To remedy this behavior, the initial setting of the wrappedValue within the sink closure is wrapped 'DispatchQueue.main.async' call. Subsequent calls are not to maintain swiftUI's animations.

[lickel]

I want to play around with the eventing, but also, thanks!

[lickel]

Nit: remove this empty line

[lickel]

Nit: .listStype(.plain)

[lickel]

Interesting... haven't seen this pattern before...
But will ask that you move this into UIKit and keep the view "pure"

[lickel]

OK, tracked it down to:

    static func fetchDefinition() -> FetchDefinition<Self> {
        let dataResetTokens: [ModelClearedToken<Self>] = [
            ModelClearedToken(),
        ]

        return FetchDefinition<Self>(
            request: { completion in
                completion(fetchAll())
            },
            objectCreationToken: ModelCreationToken<Self>(),
            dataResetTokens: dataResetTokens
        )
    }
}

Because it does completion(fetchAll()) there's no asynchronicity at all.
It's particular to this object.
I'd like to fix that in a different way than bouncing to main every time in the property wrapper.

[lickel]

I’ll ask that you revert the property wrapper and I’ll take a look at this in a separate PR

[MerinoA]

@lickel This will make the swiftUI example work as expected.

[MerinoA]

Alternatively I was able to address the issue modifying the FetchableRequest, by wrapping the fetch definition like so a new view context is guarenteed on performFetch calls.

I have a separate branch with this change. This has no impact on definitions that fetch async on a background thread and call to main for their completion.

main...MerinoA:FetchRequests:fix-fetchableRequests

But I will leave that solution up to you.

[lickel]

yup makes sense. I think I'd still like to fix it somewhere in the framework, but thanks!