SwiftUI 动画之Circle Animation 移动、旋转、显示、消失和放大联合动画。关键技术:1.从顶向下线性过渡LinearGradien;2. 垂直偏移.offset;3.设置透明度.opacity(0.5);4.旋转60度.rotationEffect(.degrees(60));5. 设置重复播放.animation(Animation.easeInOut.repeatForever(autoreverses: true).speed(1/8))