This question falls under View Building with SwiftUI , specifically the domain covering multi-view apps with navigation stacks, links, and sheets . The first blank must be NavigationLink because SwiftUI uses a navigation link inside a NavigationStack to push or present a destination view as part of the navigation hierarchy. Apple’s documentation states that people tap or click a NavigationLink to present a view inside a NavigationStack or NavigationSplitView. That matches the first code section, where tapping " Show Blue View " should navigate to BlueView().

The second blank must be .sheet because the code uses isPresented: $showRedView, which is the standard SwiftUI sheet modifier for modal presentation controlled by a Boolean binding. Apple documents sheet(isPresented:onDismiss:content:) as the modifier to use when you want to present a modal view when a Boolean becomes true. Since the button toggles showRedView, SwiftUI presents RedView() modally as a sheet.

So the completed structure is effectively:

NavigationLink( " Show Blue View " ) {

BlueView()

}

sheet(isPresented: $showRedView) {

RedView()

}

This directly aligns with SwiftUI navigation and modal presentation patterns in the App Development with Swift objective domains.