Performance of SwiftUI Views with Conditional Branching

Improve the performance of your SwiftUI views by replacing if-else and switch statements with the ternary operator. 

To illustrate the issue, let’s start with the following code that uses an if-else statement to set the foreground color of an image:

struct ContentView: View {
    @State private var isFavorite = true

    var body: some View {
        if isFavorite {
            Image(systemName: "star.fill")
                .foregroundStyle(Color.yellow)
        } else {
            Image(systemName: "star.fill")
                .foregroundStyle(Color.black)
        }
    }
}

The above code has two issues. First, there is some duplicate code. Second, toggling isFavorite between true and false causes SwiftUI to tear down and recreate the entire view. SwiftUI treats the if-else paths as separate Views and will do extra work to process the if and else paths. The same performance issue occurs with switch statements.

A quick solution to both the duplicate code and performance issue is to replace the if-else statement with a ternary operator:

Image(systemName: "star.fill")
	.foregroundStyle(isFavorite ? Color.yellow : Color.black)