How to Add Picker Default Value in iOS SwiftUI

Setting a default value for a Picker in SwiftUI is a common requirement. It helps improve the user experience by pre-selecting an option. In this blog post, we’ll explore how to set a default value for a Picker in SwiftUI.

Why Set a Default Value?

Before diving into the code, let’s understand why setting a default value is important. A default value can guide the user and save time. It can also prevent errors by ensuring that a valid option is always selected.

The Basics of SwiftUI Picker

A Picker in SwiftUI is similar to a dropdown menu. You can create one using the Picker view. Here’s a simple example:

Picker("Choose a number", selection: $selectedNumber) {
    ForEach(0..<10) { number in
        Text("\(number)").tag(number)
    }
}

Set a Default Value

To set a default value, you need to initialize the variable that holds the selected value. In the example above, you would set selectedNumber to your default value like so:

@State private var selectedNumber = 5

Use .onAppear()

Another way to set a default value is by using the .onAppear() modifier. This is useful when the default value is dynamic or fetched from an API.

Picker("Choose a number", selection: $selectedNumber)
    .onAppear() {
        self.selectedNumber = 5
    }

A Complete Example

Here’s a full example that combines everything:

struct ContentView: View {
    @State private var selectedNumber = 0

    var body: some View {
        Picker("Choose a number", selection: $selectedNumber) {
            ForEach(0..<10) { number in
                Text("\(number)").tag(number)
            }
        }
        .onAppear() {
            self.selectedNumber = 5
        }
    }
}

Conclusion

Setting a default value for a Picker in SwiftUI is straightforward. You can either initialize the selection variable with a default value or use the .onAppear() modifier. Both methods are effective and can enhance the user experience.