1.用到的技术点 1)Generics   泛型 2)ViewBuilder 视图构造器 3)PreferenceKey偏好设置 4)MatchedGeometryEffect几何效果2.创建枚举选项卡项散列，TabBarItem.swiftimportFoundationimportSwiftUI//structTabBarItem:Hashable{//leticonName:String//lettitle:String//letcolor:Color//}///枚举选项卡项散列enumTabBarItem:Hashable{casehome,favorites,profile,mess