# 設定動畫

## 重點

* 用 **@State private var** 來宣告 view state，並用來控制 view 的屬性。
* 用 **ternary opeartor** (`condition ? trueValue : falseValue`) 來設定可產生動畫的屬性。
* 用 view.**animation**() 來加入動畫。
* 用 view.**onTapGesture**() 來設定「**觸控功能**」（如：改變 view state）

{% tabs %}
{% tab title="main" %}

```swift
/*
 Design+Code - SwiftUI for iOS 13
 https://designcode.io/swiftui-animations-and-states
 */

import SwiftUI
import PlaygroundSupport

struct ContentView: View {
    
    // view states
    @State private var show = false  // ⭐️ 加入 view state
    
    // view body
    var body: some View {
        ZStack {
            TitleView()
                .blur(radius: show ? 20 : 0)  // ⭐️ 由 state 控制「模糊化」程度
                .animation(.default)          // ⭐️ 加入動畫
            
            BackCard(.purple)
                .scaleEffect(0.9)
                .offset(x: 0, y: show ? -400 : -40) // ⭐️ 由 state 控制「平移」程度
                .rotationEffect(.degrees(show ? 0 : 10))  // ⭐️ 由 state 控制「旋轉」程度
                .rotation3DEffect(.degrees(10), axis: (x: 1, y: 0, z: 0))
                .blendMode(.hardLight)
                .animation(.easeInOut(duration: 0.5))     // ⭐️ 加入動畫
            
            BackCard(.pink)
                .scaleEffect(0.95)
                .offset(x: 0, y: show ? -200 : -20)
                .rotationEffect(.degrees(show ? 0 : 5))
                .rotation3DEffect(.degrees(5), axis: (x: 1, y: 0, z: 0))
                .blendMode(.hardLight)
                .animation(.easeInOut(duration: 0.3))
            
            // main card
            Card()
                .blendMode(.hardLight)
                .onTapGesture { self.show.toggle() }  // ⭐️ 由觸控來控制 state
            
            BottomCard()
                .blur(radius: show ? 20 : 0)
                .animation(.default)
            
        } // ZStack (container)
            .frame(maxWidth: .infinity, maxHeight: .infinity)
            .background(Color.white)
    }
}

PlaygroundPage.current.setLiveView(ContentView())
```

{% endtab %}

{% tab title="截圖" %}
![Cards with animations](/files/-MG6OMY334oAHm1xj6i2)
{% endtab %}
{% endtabs %}


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