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How to adjust the opacity of a view

Paul Hudson    @twostraws   

Updated for Xcode 13.0

Any SwiftUI view can be partially or wholly transparent using the opacity() modifier. This accepts a value between 0 (completely invisible) and 1 (fully opaque), just like the alpha property of UIView in UIKit.

For example, this creates a text view with a red background, then gives it 30% opacity:

Text("Now you see me")
    .padding()
    .background(Color.red)
    .opacity(0.3)

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The text “Now you see me” in a red rectangle. Both are translucent.

Modifying opacity is extremely fast – certainly something you can do as often as you need. To demonstrate that, the following code adjusts text opacity using a slider, and you’ll see you can move it around as fast and as much as you like without any performance hit:

struct ContentView: View {
    @State private var opacity = 0.5

    var body: some View {
        VStack {
            Text("Now you see me")
                .padding()
                .background(Color.red)
                .opacity(opacity)

            Slider(value: $opacity, in: 0...1)
                .padding()
        }
    }
}

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