这个技术项目起步比较容易,经过几番曲折,然后发展为更高级的动画,但是我希望它给您一个强大而灵活的想法!– SwiftUI的动画系统。

正如我之前所说,动画既要使您的应用看起来很棒,又要增加额外的含义。因此,除了让视图突然消失之外,您还可以添加一个过渡来帮助用户了解正在发生的变化吗?

另外,不要忘记在用户界面中看起来很有趣。我一直以来排名第一的最喜欢的iOS动画是Apple移至iOS 7时抛弃的动画,它是用于在电子钱包应用中删除通行证的动画–出现了金属粉碎机,将通行证切成十几条,然后掉了下来。它仅比当前动画花费了几分之一秒的时间,但它也很有趣。

挑战

返回到Guess the Flag项目并添加一些动画:

  • 当您点击正确的标志时,使其在Y轴上旋转360度。
  • 使其他两个按钮淡出至25%的不透明度。
  • 如果您点击了错误的标志?好吧,这取决于您–发挥创意!

代码

点击错误的标志后,正确的标志会有一个无限循环的缩放动画

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//
// ContentView.swift
// GuessTheFlag
//
// Created by 张洪Hoo on 2020/1/20.
// Copyright © 2020 张洪Hoo. All rights reserved.
//

import SwiftUI

struct ImgView: ViewModifier {
func body(content: Content) -> some View {
content
.clipShape(Capsule())
.overlay(Capsule().stroke(Color.black, lineWidth: 1))
.shadow(color: .black, radius: 2)
}
}

extension View {
func flagimg() -> some View {
self.modifier(ImgView())
}
}

struct ContentView: View {
@State private var showingScore = false
@State private var scoreTitle = ""
@State private var score = 0

@State private var countries = ["Estonia", "France", "Germany", "Ireland", "Italy", "Nigeria", "Poland", "Russia", "Spain", "UK", "US"].shuffled()
@State private var correctAnswer = Int.random(in: 0...2)

@State private var animationAmount:[Double] = [0,0,0]
@State private var animationOpacity:[Double] = [1,1,1]
@State private var animationSize:[CGFloat] = [1,1,1]

var body: some View {
ZStack {
LinearGradient(gradient: Gradient(colors: [.blue, .black]), startPoint: .top, endPoint: .bottom).edgesIgnoringSafeArea(.all)
VStack(spacing: 30.0) {
VStack {
Text("Tap the flag of")
.foregroundColor(Color.white)

Text(countries[correctAnswer])
.font(.largeTitle)
.fontWeight(.black)
.foregroundColor(Color.white)

Text("Score: \(score)")
.foregroundColor(Color.white)
.padding(.top)

}

ForEach(0 ..< 3) { number in

Button(action: {

self.flagTapped(number)
// self.askQuestion()
}) {
Image(self.countries[number])
.renderingMode(.original)
.flagimg()


}.rotation3DEffect(Angle(degrees: self.animationAmount[number]), axis: (x: 0, y: 1, z: 0))
.opacity(self.animationOpacity[number])
.animation(.default)
.scaleEffect(self.animationSize[number])
.animation( Animation.easeInOut(duration: 1)
.repeatForever(autoreverses: true))
}

Spacer()

}

}.alert(isPresented: $showingScore) {
Alert(---
title: Text(scoreTitle), message: Text("Your score is \(score)"), dismissButton: .default(Text("Continue")))
}
}
func flagTapped(_ number: Int) {
if number == correctAnswer{
self.animationAmount[self.correctAnswer] += 360.0
scoreTitle = "Correct"
self.score += 1

for num in 0 ..< 3 {
if num == self.correctAnswer {
self.animationOpacity[num] = 1
}else {
self.animationOpacity[num] = 0.25
}
}

}else {
scoreTitle = "Wrong![]That's \(countries[number]) flag"
self.score -= 1

self.animationSize[correctAnswer] = 1.2
for num in 0 ..< 3 {
if num == self.correctAnswer {
self.animationOpacity[num] = 1
}else {
self.animationOpacity[num] = 0.25
}
}
}



showingScore = true
}

func askQuestion(){

countries.shuffle()
correctAnswer = Int.random(in: 0...2)
animationOpacity = [1,1,1]
animationSize = [1,1,1]
}
}

struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}

参考资料

查看下一天的SwiftUI学习笔记

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