Macro picker_bound 

macro_rules! picker_bound {
    ($title:expr, $state:expr, $($row:expr),* $(,)?) => { ... };
}

Picker(_:selection:) over rows, bound to Rust state.

The rows are a @ViewBuilder block in Swift, so they are a list here rather than something the caller has to wrap in a tuple_view by hand.

picker_bound!("Theme", &theme, text("System").tag_int(0), text("Dark").tag_int(1))