Implicit animations (.animation modifier) in iOS Swift

Introduction

Implicit animations make UI changes smooth and natural without extra code. They help your app feel alive and responsive.

When you want a button to smoothly change color when tapped.

When a shape changes size and you want the change to animate automatically.

When toggling a view's visibility with a fade effect.

When moving a view from one place to another with a smooth slide.

When you want to add polish to your app with simple animations.

Syntax

iOS Swift

view.property = newValue
.animation(Animation, value: trigger)

The .animation modifier attaches an animation to changes of the view's property.

The value parameter tells SwiftUI when to run the animation by watching for changes.

Examples

This animates the circle's color smoothly when isOn changes.

iOS Swift

Circle()
  .frame(width: 100, height: 100)
  .foregroundColor(isOn ? .green : .red)
  .animation(.easeInOut, value: isOn)

This animates the rectangle's size changes with a spring effect.

iOS Swift

Rectangle()
  .frame(width: size, height: size)
  .animation(.spring(), value: size)

Sample App

This app shows a circle that changes size and color smoothly when you tap the button.

iOS Swift

import SwiftUI

struct ContentView: View {
  @State private var isBig = false

  var body: some View {
    VStack {
      Circle()
        .frame(width: isBig ? 200 : 100, height: isBig ? 200 : 100)
        .foregroundColor(isBig ? .blue : .orange)
        .animation(.easeInOut(duration: 1), value: isBig)

      Button("Toggle Size") {
        isBig.toggle()
      }
      .padding()
    }
  }
}

Important Notes

Always provide the value parameter to tell SwiftUI what to watch for changes.

Without .animation, changes happen instantly with no smooth effect.

You can customize animation types like .easeInOut, .spring(), or create your own.

Summary

Implicit animations make UI changes smooth with little code.

Use the .animation modifier with a value to animate property changes.

This improves user experience by making apps feel lively and polished.