This question belongs to View Building with SwiftUI , especially the domain on creating multiple views to implement app logic and sharing values between views. In FirstView, the value typed into the TextField is stored in number, which is a String. When the NavigationLink is tapped, the code passes Int(number) ?? 0 into SecondView. In Swift, converting a string to an integer with Int(...) uses an optional initializer, which means it returns an optional value and will produce nil if the string cannot be converted. The ?? 0 nil-coalescing operator then supplies 0 if conversion fails.
Inside SecondView, the body is:
Color(passedNumber == 3 ? .blue : .red)
This uses the ternary conditional operator. If passedNumber equals 3, the displayed color is blue; otherwise, it is red. Therefore, entering 3 into the TextField causes Int(number) to become 3, which makes the condition passedNumber == 3 true and displays a blue canvas. Any other listed number results in red.
So the correct answer is A. 3 . This matches the SwiftUI pattern of taking user input, converting it to the needed type, passing it into another view, and rendering UI conditionally based on that value.
