SOLVED: View with an optional @ViewBuilder parameter - Avoiding "generic parameter could not be inferred"? – SwiftUI

SOLVED: View with an optional @ViewBuilder parameter - Avoiding "generic parameter could not be inferred"?

@tiltowait

Jun '21

I have the following View:

struct ReferenceRow<Content: View>: View {

  let title: String
  let subtitle: String?
  let icon: Image?
  let secondary: () -> Content?

  init(
    title: String,
    subtitle: String? = nil,
    icon: Image? = nil,
    @ViewBuilder secondary: @escaping () -> Content? = { nil }
  ) {
    self.title = title
    self.subtitle = subtitle
    self.icon = icon
    self.secondary = secondary
  }

  var body: some View {
    // ...
  }

}

However, if I try to omit secondary (such as with ReferenceView(title: "Title", subtitle: "Subtitle"), Xcode complains that "Generic parameter 'Content' could not be inferred". Is there any way to make this work?

@Hatsushira HWS+

Jun '21

In my understanding you can't do it this way. Swift needs to know which type Content will be when ReferenceRow is initiated.

When you omit secondary then Swift doesn't know which type Content will have. To be specific. If you omit secondary you have to initiate ReferenceRow<YourViewTypeHere>(title: "Title", subtitle: "Subtitle") like this.

@tiltowait

Jun '21

Thanks. A little disappointing. I decided to remove the generic entirely after realizing the Content was always going to be a color accent, and that its shape and position is invariable.

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