Help with ViewBuilders and SwiftUI (Xcode 12, Swift 5.3)

Question

Hello Everyone,

Posted it originally in the Using Swift section here:
https://forums.swift.org/t/help-viewbuilder-and-swiftui-issue-swift-5-3/40862

A colleague and I are trying to refactor some code to take advantage of new features in Swift 5.3 and more specifically of the view builder changes that would allow us to remove some of the AnyView casting we were doing.

We noticed that this will not work unless we manually add the @ViewBuilder annotation before of the body property and we thought this would not be needed as it should be treated as a special case and inherit the ViewBuilder was inferred by the compiler ( https://developer.apple.com/wwdc20/10170 1 ): <you can see the pictures in the Swift.org forum thread above>.

Do you see a silly mistake in there?

Thank you in advance for your help!

Kind Regards,

Goffredo

713

Posted by

Goff.Marocchi

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Answer 1

An update from the quoted thread above:

Example:

Code Block struct Test: View {
    let value: Int?
    var body: some View {
        if case let value? = value {
            Text("\(value)")
        } else {
            Text("Test")
        }
    }
}

I tried to drop your example in it and it does not compile in the existing project. It does compile in a brand new iOS only project, but it does not compile in a brand new macOS project (shared sample iOS and macOS projects): https://www.icloud.com/iclouddrive/01bKAFXVd82HpGZ-3R7RExKeA#ViewBuilder_iOS_macOS
Not sure why it would not work for macOS, there could be the embarrassing thing I was missing and I should have explained it is an iOS + macOS app.

So it works as a pure iOS project, but not as a pure macOS project. Will be creating a Feedback report and post the ID here.

Posted by

Goff.Marocchi

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Answer 2

An update from the quoted thread above:

Example:

Code Block struct Test: View {
    let value: Int?
    var body: some View {
        if case let value? = value {
            Text("\(value)")
        } else {
            Text("Test")
        }
    }
}

I tried to drop your example in it and it does not compile in the existing project. It does compile in a brand new iOS only project, but it does not compile in a brand new macOS project (shared sample iOS and macOS projects): https://www.icloud.com/iclouddrive/01bKAFXVd82HpGZ-3R7RExKeA#ViewBuilder_iOS_macOS
Not sure why it would not work for macOS, there could be the embarrassing thing I was missing and I should have explained it is an iOS + macOS app.

So it works as a pure iOS project, but not as a pure macOS project. Will be creating a Feedback report and post the ID here.

Posted by

Goff.Marocchi

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Answer 3

FB8800652 (ViewBuilder is not inferred for a SwiftUI's body property for a macOS Target)

Tapped the “Answered” icon by mistake and I cannot undo it :/...

Posted by

Goff.Marocchi

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Answer 4

Fixed in Xcode 12.2 Beta 3

Posted by

Goff.Marocchi

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Help with ViewBuilders and SwiftUI (Xcode 12, Swift 5.3)

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