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Ternary Operators

Last updated on 22 Oct 2024.

Arthan

Jia Chen

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Ternary Operators

Last updated on 22 Oct 2024.

Arthan

Jia Chen

Playground on iPad

Playground on Mac

Xcode

Ternary Operators

Last updated on 22 Oct 2024.

Arthan

Jia Chen

Playground on iPad

Playground on Mac

Xcode

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Ternary Operators in Swift

Ternary operators are composed of 3 key parts—the condition, the value if true, and the value if false.

It also goes by the question mark colon operator ?:
Or you could call it the WTF operator (What ? True : False)

Ternary operators can be used to cut down on the amount of code required. In the following example, a ternary operator can be used to customize a greeting for a user based on whether or not they are logged in.

let isUserLoggedIn: Bool = true

let greeting = isUserLoggedIn ? "Welcome Back!" : "Please log in."

An equivalent If Statement would look something like this.

let isUserLoggedIn: Bool = true

let greeting: String

if isUserLoggedIn {
    greeting = "Welcome Back!"
}  else {
    greeting = "Please log in."
}

Ternary Operators in SwiftUI

In the following example, a ternary operator is used to display a different message depending on whether a user is logged in.

struct ContentView: View {
    @State private var isUserLoggedIn = false
    
    var body: some View {
        Text(isUserLoggedIn ? "Welcome back!" : "Please log in.")
    }
}

This can also be achieved with Conditional Rendering and an If Statement.

struct ContentView: View {
    var body: some View {
        if userIsLoggedIn {
            Text("Welcome back!")
        } else {
            Text("Please log in.")
        }
    }
}

The ternary operator is particularly useful when applying multiple modifiers on a view.

struct ContentView: View {
    @State private var isUserLoggedIn = false
    
    var body: some View {
        Text(isUserLoggedIn ? "Welcome back!" : "Please log in.")
            .fontWeight(.heavy)
            .fontDesign(.rounded)
    }
}

Compared to an equivalent If-Statement.

struct ContentView: View {
    var body: some View {
        if userIsLoggedIn {
            Text("Welcome back!")
                .fontWeight(.heavy)
                .fontDesign(.rounded)
        } else {
            Text("Please log in.")
                .fontWeight(.heavy)
                .fontDesign(.rounded)
        }
    }
}

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Concepts

Ternary Operators

Concepts

Ternary Operators

Concepts

Ternary Operators

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Ternary Operators in Swift

Ternary Operators in SwiftUI

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Swift Fundamentals

A collection of articles and examples on Swift fundamentals.

See Also

Switch Statements

A control-flow statement to compare against several different paths.