how to create an animated page transition?

To create an animated page transition in SwiftUI, you can use custom transitions and modifiers to achieve the desired effect. Here are some steps and examples based on the content from WWDC sessions:

Using Built-in Transitions:
- SwiftUI provides built-in transitions like opacity, scale, and combined transitions. You can start with these to create simple animations.
- Example:
```
.transition(.opacity)
.transition(.scale)
.transition(.opacity.combined(with: .scale))
```

Creating Custom Transitions:

For more complex animations, you can create custom transitions by conforming to the Transition protocol.

Example from the session "Create custom visual effects with SwiftUI":

struct Twirl: Transition {
    func body(content: Content, phase: TransitionPhase) -> some View {
        content
            .scaleEffect(phase == .identity ? 1 : 0.5)
            .opacity(phase == .identity ? 1 : 0)
            .rotationEffect(Angle(degrees: phase == .identity ? 0 : 360))
    }
}

.transition(Twirl())

Zoom Transitions:
- The new zoom transition in iOS 18 can be used to create a smooth and interactive transition effect.
- Example from the session "Enhance your UI animations and transitions":
```
.navigationTransitionStyle(.zoom)
```
Combining Effects:
- You can combine multiple effects like blur, rotation, and brightness to create a more dynamic transition.
- Example from the session "Create custom visual effects with SwiftUI":
```
.blur(radius: phase == .identity ? 0 : 10)
.rotationEffect(Angle(degrees: phase == .identity ? 0 : -360))
.brightness(phase == .identity ? 0 : 0.5)
```

For a detailed walkthrough, you can refer to the following sessions:

Create custom visual effects with SwiftUI (09:10)
Enhance your UI animations and transitions (02:07)

These sessions provide comprehensive examples and explanations on how to implement and customize transitions in SwiftUI.