How does the application determine which page or component users have selected when clicking?

In iOS applications, the selection of a page or component upon clicking is usually determined through event handlers, such as delegate methods or target-action. For example, when a button or list item is pressed, a method is called that knows which specific item was selected, and based on it, a transition to the corresponding screen or display of the required component occurs.

In UIKit, this is often implemented through IBAction or delegates, and in SwiftUI — through state binding and navigation links (NavigationLink), which automatically track user selection.

Example with UIKit:

@IBAction func buttonTapped(_ sender: UIButton) {
    if sender == firstButton {
        // Transition to the first page
    } else if sender == secondButton {
        // Transition to the second page
    }
}

In SwiftUI:

NavigationLink(destination: DetailView()) {
    Text("Go to details")
}